Symphony No. 4 (Bruckner)

Symphony No. 4
"Romantic"
by Anton Bruckner

A portrait of Anton Bruckner, c. 1860
Key E-flat major
Catalogue WAB 104
Composed
  • 1873 (1873)–1874
  • 1878 (1878)–1880
  • 1887 (1887)–1888
Dedication Prince Konstantin of Hohenlohe-Schillingsfürst
Published
Recorded 1936 (1936) Karl Böhm, Dresden Staatskapelle
Movements 4
Premiere
Date 20 February 1881 (1881-02-20)
Location Vienna
Conductor Hans Richter
Performers Vienna Philharmonic

Anton Bruckner's Symphony No. 4 in E-flat major (WAB 104) is one of the composer's most popular works. It was written in 1874 and revised several times through 1888. It was dedicated to Prince Konstantin of Hohenlohe-Schillingsfürst. It was premiered in 1881 by Hans Richter in Vienna to great acclaim.

The symphony's nickname of Romantic was used by the composer himself. It does not refer to the modern conception of romantic love but rather the medieval romance as depicted in the operas Lohengrin and Siegfried of Richard Wagner.[1]

Description

The symphony has four movements:

  1. Bewegt, nicht zu schnell (With motion, not too fast) (E-flat major)
  2. Andante, quasi allegretto (C minor)
  3. Scherzo. Bewegt (With motion) – Trio: Nicht zu schnell (Not too fast) (B-flat major)
  4. Finale: Bewegt, doch nicht zu schnell (With motion, but not too fast) (E-flat major)

These tempo markings are from the 1880 version. The 1888 version, edited by Benjamin Korstvedt in the Gesamtausgabe (Band IV Teil 3) has slightly different tempo marking, plus metronome markings.

  1. Ruhig bewegt (nur nicht schnell) (Quiet motion (just not fast)) (Allegro molto moderato) ( = 72)
  2. Andante ( = 66)
  3. Bewegt (With motion) ( = 126)
  4. Mäßig bewegt ( = 72)

Programme

There exists much evidence that Bruckner had a program in mind for the Fourth Symphony. In a letter to conductor Hermann Levi of 8 December 1884, Bruckner wrote: "In the first movement after a full night's sleep the day is announced by the horn, 2nd movement song, 3rd movement hunting trio, musical entertainment of the hunters in the wood.[2] There is a similar passage in a letter from the composer to Paul Heyse of 22 December 1890: "In the first movement of the "Romantic" Fourth Symphony the intention is to depict the horn that proclaims the day from the town hall! Then life goes on; in the Gesangsperiode [the second subject] the theme is the song of the great tit [a bird] Zizipe. 2nd movement: song, prayer, serenade. 3rd: hunt and in the Trio how a barrel-organ plays during the midday meal in the forest.[2]

The autograph of the Scherzo and Finale of the 1878 version of the symphony contains markings such as Jagdthema (hunting theme), Tanzweise während der Mahlzeit auf der Jagd (dance tune during the lunch break while hunting) and Volksfest (people's festival).[2] In addition to these clues that come directly from Bruckner, the musicologist Theodor Helm communicated a more detailed account reported via the composer's associate Bernhard Deubler: "Mediaeval city -- Daybreak -- Morning calls sound from the city towers -- the gates open -- On proud horses the knights burst out into the open, the magic of nature envelops them -- forest murmurs -- bird song -- and so the Romantic picture develops further...[2]

There does not seem to be any clear hint of a program for the third version (1880) of the symphony's finale.[2]

Versions

Since the 1930s Bruckner scholars have generally recognised three principal versions of the Fourth Symphony, but two of these exist in more than one form:

At least seven authentic versions and revisions of the Fourth Symphony have been identified.

1874 version

Bruckner's original version, published in an edition by Leopold Nowak in 1975, was composed between 2 January and 22 November 1874. This version was never performed or published during the composer's lifetime, though the Scherzo was played in Linz on 12 December 1909. The first complete performance was given in Linz more than a century after its composition on 20 September 1975 by the Munich Philharmonic Orchestra conducted by Kurt Wöss. The first commercial recording of the 1874 version was made in September 1982 by the Frankfurt Radio Symphony Orchestra conducted by Eliahu Inbal (CD 2564 61371-2).

1878 version

When he had completed the original version of the symphony, Bruckner turned to the composition of his Fifth Symphony. When he had completed that piece he resumed work on the Fourth, though it is possible that he made some revisions to the latter in 1876 or 1877. Between 18 January and 30 September 1878 he thoroughly revised the first two movements and replaced the original finale with a new movement entitled Volksfest ("Popular Festival"). This Volksfest finale was published as an appendix to Robert Haas's edition of 1936 and in a separate edition by Leopold Nowak in 1981.

In December 1878 Bruckner replaced the original Scherzo with a completely new movement, which is sometimes called the "Hunt" Scherzo (Jagd-Scherzo). In a letter to the music critic Wilhelm Tappert (October 1878), Bruckner describes the new movement thus: "[the Scherzo] represents the hunt, whereas the Trio is a dance melody which is played to the hunters during their repast". The original title of the Trio reads: Tanzweise während der Mahlzeit auf der Jagd ("Dance melody during the hunters' meal").

1880 version (aka 1878/1880)

After the lapse of almost a year (during which he composed his String Quintet in F Major), Bruckner took up his Fourth Symphony once again. Between 19 November 1879 and 5 June 1880 he composed a new finale – the third, though it shares much of its thematic material with the first version[3] – and discarded the Volksfest finale. Thus the 1880 version is the same as the 1878 version but with a new finale. This was the version performed at the work's premiere on 20 February 1881, which was the first premiere of a Bruckner symphony not to be conducted by Bruckner himself. This version is sometimes referred to as the 1878/80 version.

1881 revision

The 1881 version is the same as the 1880 version but includes some changes made after the first performance of the latter – notably a cut in the slow movement and a reworking of the finale. It is available in an edition by Robert Haas, which was published in 1936, based on Bruckner's manuscript in the Austrian National Library.[4]

1886 revision

The 1886 version is the same as the 1881 version but includes a number of changes made by Bruckner while preparing a score of the symphony for Anton Seidl, who took it with him to New York. This version was published in an edition by Nowak in 1953, based on the original copyist's score, which was rediscovered in 1952 and is now in the collection of Columbia University. In the title of Nowak's publication, it was confusingly described as the "1878-1880 version". It was performed in New York by Seidl on 4 April 1888.

1887 version

With the assistance of Ferdinand Löwe, and probably also Franz and Joseph Schalk, Bruckner thoroughly revised the symphony in 1887–88 with a view to having it published. Although Löwe and the Schalks made some changes to Bruckner's score, these are now thought to have been authorized by Bruckner. This version was first performed to great acclaim in Vienna on 20 January 1888 by the Vienna Philharmonic Orchestra under the baton of Hans Richter.

The only surviving manuscript which records the compositional process of this version is the Stichvorlage, or engraver's copy of the score, which was prepared for the symphony's publisher Alfred J. Gutmann of Vienna. The Stichvorlage was written down by three main copyists whose identities are unknown, though it is possible that they were none other than Löwe and Franz and Joseph Schalk. One of the copyists copied out the 1st and 4th movements, while the others each copied out one of the inner movements. Some tempi and expression marks were added in a fourth hand; these may have been inserted by Hans Richter during rehearsals for the premiere in January 1888, or even by Bruckner himself, who is known to have taken an interest in such matters. The Stichvorlage is now in an inaccessible private collection in Vienna; there is, however, a set of black-and-white photographs of the entire manuscript in the Wiener Stadtbibliothek (A-Wst M.H. 9098/c).[5]

1888 revision

In February 1888, Bruckner made extensive revisions to all four movements after having heard the premiere of the 1887 version the previous month. These changes were entered in Bruckner's own hand into the Stichvorlage, which he then dated. The Stichvorlage was sent to the Viennese firm of Albert J. Gutmann sometime between 15 May and 20 June 1888. In September 1889 the score was published by Gutmann. This was the first edition of the symphony to be published in the composer's lifetime. In 1890 Gutmann issued a corrected text of this edition, which rectified a number of misprints.

The 1888 version is sometimes referred to by Bruckner scholars as the "revised version".

Mahler reorchestration

Gustav Mahler made an arrangement of the 1888 version which is heavily cut and reorchestrated. It is available in a recording by Gennadi Rozhdestvensky.

The following table summarises the details of the different versions.

Year Common Designation Korstvedt Redlich Cooke Other Designation Source Printed Editions
1874
I
I
I
Original Version
Urfassung
Nowak 1975
1878
II
IIa
II
Volksfest Version
Haas 1936
Haas 1944
Nowak 1981 (Finale)
1880
IIb
III
First Definitive Vienna Version
1878/80 Version
Unpublished
1881 Karlsruhe Version
Originalfassung
1878/80 Version
Autograph: A-Wn Mus. Hs. 19.476 Haas 1936
Haas 1944
1886 Revised New York Version
1878/80 Version
Copyist's Score: Columbia Nowak 1953
1887
III
III
IV
Löwe/Schalk
Stichvorlage (private collection)
Photographs: A-Wst M.H. 9098/c
Unpublished
1888 Schalk & Löwe Version
Endfassung
Fassung letzter Hand
Stichvorlage (private collection)
Photographs: A-Wst M.H. 9098/c
Gutmann 1889
Wöss 1927
Redlich 1955
Korstvedt 2004

Bruckner's Fourth Symphony and the "Bruckner Problem"

Any critical appraisal of Bruckner's Fourth Symphony must take into account the so-called Bruckner Problem – i.e. the controversy surrounding the degrees of authenticity and authorial status of the different versions of his symphonies. Between 1890 and 1935 there was no such controversy as far as the Fourth was concerned: Gutmann's print of the symphony, the 1888 version, was unchallenged. British musicologist Donald Francis Tovey's analysis of the symphony mentioned no other version, nor does the Swiss theorist Ernst Kurth. Gutmann's version was the one performed by the leading conductors of the day: Mahler,[6] Weingartner, Richter and Fischer.

In 1936, Robert Haas, editor of the Gesamtausgabe (the critical edition of all of Bruckner's works), dismissed the version printed in 1889 as being without authenticity, saying that "the circumstances that accompanied its publication can no longer be verified"[4] and calling it "a murky source for the specialist".[4] In Haas's opinion the 1880 version was the Fassung letzter Hand (i.e. the last version of the symphony to be transmitted in a manuscript in Bruckner's own hand). It later transpired that this assertion is not entirely true, but when Haas denied authorial status to the 1889 version he was unaware that the Stichvorlage from which that print was taken has extensive revisions in Bruckner's own hand, which Bruckner made in February 1888 after the premiere of the 1887 version of the symphony. To account for the fact that Bruckner had allowed the 1888 version to be printed, Haas created the now-popular image of Bruckner as a composer with so little confidence in his own orchestral technique that he was easily persuaded to accept the revisions of others like Löwe and the Schalks.

Haas's 1936 edition contained the entire symphony based on Bruckner's 1881 autograph and included the Volksfest finale in an appendix: he described this edition as the "original version" (Originalfassung). He planned a second volume containing the earlier 1874 version of the symphony, but this was never completed.[7]

In 1940 Alfred Orel announced the rediscovery of the Stichvorlage from which the 1888 version had been printed. He noted that Bruckner had emended it himself and in 1948 declared it the true Fassung letzter Hand. Even Haas appears to have had second thoughts on the matter when he learned of the existence of the Stichvorlage. In 1944 he announced his intention to restore the 1888 version to the Bruckner Gesamtausgabe; but before he could do this he was replaced as editor by Leopold Nowak, who was not yet convinced that the 1888 version was authentic. Nowak rejected the evidence of the Stichvorlage on the grounds that Bruckner had not signed it. He also repeated – and revised – some of the arguments Haas had invoked to cast doubt on Bruckner's involvement in the preparation of the 1887 version.

Throughout the second half of the twentieth century most commentators accepted Haas's and Nowak's arguments without taking the trouble to investigate the matter any further.[8] The rediscovery of the copyist's score of the 1886 version was the only significant change to the Gesamtausgabe during Nowak's long editorship (1944-198?). Nowak issued critical editions of the original 1874 version (1975), the 1886 version (1953) and the Volksfest finale of the 1878 version (1981), as well as a new edition of the 1881 version (1981). Gutmann's print of the 1888 version, however, remained beyond the pale as far as Nowak was concerned.

Critical appreciation of the symphony took an interesting turn in 1954, when Eulenburg issued a new edition of the 1888 version by the German-born British musicologist Hans F. Redlich. According to Redlich, the publication of the revised version in 1889 did not mark the end of the Fourth Symphony's long process of composition and revision, as most commentators had assumed, for on 18 January 1890 Bruckner supposedly began to indite yet another version of the symphony:

"The strangest feature in this tangle of conflicting evidence is the fact that the so called Endfassung (final version) of the symphony which – according to R. Haas – combined versions II and III [i.e. essentially the same as the 1880 version] and is embodied in HS 19476 of the Nat. Bibl. Vienna Austrian National Library, seems to have been put on paper after the issue of the "revised version" (i.e [the published 1888 version]). This emerges clearly from the Facsimile of its first page [published as Plate IV in R. Haas, Anton Bruckner (Potsdam, 1934), p. 128], which bears the date of its commencement: Vienna January 18, 1890. It is possible to see in this MS score as well as in its date a silent protest of Bruckner's against the published score of 1889."[9]

Redlich buttressed this argument by questioning the authenticity of a number of emendations to the score which he considered alien to Bruckner's native style. Among these, the following may be noted: the introduction of piccolo and cymbals in the 76th bar of the finale; the use of pp cymbals in bar 473 of the finale; and the use of muted horns in bar 147 of the finale, the aperto command for which is omitted in bar 155.[10]

In 1969 Deryck Cooke repeated these arguments in his influential series of articles The Bruckner Problem Simplified, going so far as to claim that Bruckner "withheld his ultimate sanction by refusing to sign the copy sent to the printer".[11] Cooke, who referred to the 1888 version as the "completely spurious … Löwe/Schalk score", concluded that the existence of the alleged manuscript of 1890 to which Redlich had first drawn attention effectively annulled all revisions made after 1881.

In 1996, however, critical opinion of the Fourth Symphony was turned on its head by the American musicologist Benjamin Korstvedt, who demonstrated that the manuscript referred to by Redlich and Cooke does not in fact exist: "Were it true that Bruckner made such a copy, Cooke's claim would merit consideration. But Bruckner never did. Redlich and Cooke were misled by a photograph in Haas's biography of Bruckner. This photograph, which shows the first page of Bruckner's autograph score of the second version, is cropped in such a way that the date 18. Jänner 1878 – which is mentioned by Haas – seems to read 18 Jänner 1890"[12]

Korstvedt has also refuted Haas's oft-repeated argument that Bruckner was a diffident composer who lacked faith in his own ability and was willing to make concessions that contravened his own artistic judgement. No evidence has ever been adduced in support of this assessment of the composer. On the contrary, there are first-hand accounts from Bruckner's own associates that it was impossible to persuade him to accept emendations against his own better judgement.

It is Korstvedt's contention that while the preparation of the 1888 version was indeed a collaborative effort between Bruckner, Löwe, and probably also Franz and Joseph Schalk, this in no way undermines its authorial status; it still represents Bruckner's final thoughts on his Fourth Symphony and should be regarded as the true Endfassung or Fassung letzter Hand. There is no evidence that Bruckner "refused" to sign the Stichvorlage. He may have omitted to do so, but this is also true of other Bruckner manuscripts whose authenticity is not doubted. Furthermore, there is no real evidence that Bruckner was forced to accept revisions in order to get the work published, as Haas claimed. The only condition that Gutmann made prior to publication was that he be paid 1,000 fl. in advance to cover his costs. Once this money was delivered to him, he would have been quite happy, presumably, to print whatever version of the symphony Bruckner sent him.

In 2004 Korstvedt issued the first modern edition of the 1888 version of the symphony for the Gesamtausgabe.[13]

Composition history

The following table summarizes the Fourth Symphony's complicated history of composition (or Wirkungsgeschichte, to use the critical term preferred by Bruckner scholars). The principal sources for these data are Korstvedt (1996) and Redlich (1954). (B = Bruckner; FS = Fourth Symphony; mvt = movement.)

1874
2 January
24 January
21 February
10 April
13 June
25 July
5 August
22 November
-
1875
passim
-
1876
August
September
-
12 October
-
-
1878
18 January
1 August
30 Sept
9 October
-
December
-
1879
19 November
-
1880
5 June
-
1881
20 February
??
December
-
1885
??
-
1886
??
4 June
??
Summer
August
1 October
October?
16 November
-
1887
3 January
Spring?
9 May
December?
14 December
-
1888
22 January
February
23 February
27 February
-
9 March
4 April
15 May
20 June
-
1889
September
-
1890
??
10 December
11 December
-
1891
18 April
??
-
1892
Spring
15 June
-
B sketches the 1st mvt of his FS
1st mvt: sketch of score is completed
1st mvt: full score and instrumentation are worked out
B begins to sketch 2nd mvt
B begins to sketch 3rd mvt
3rd mvt is completed
B begins to sketch 4th mvt
1st version (1874) of the FS is completed
-
-
Unsuccessful attempts by B to have his FS performed
-
-
B meets the progressive music critic Wilhelm Tappert at the inaugural Bayreuth Festival
Tappert persuades the conductor Benjamin Bilse to perform the FS in Berlin
B sends Bilse a score and a set of orchestral parts
B writes to Tappert, declaring his intention to thoroughly revise the FS before any performance
He engages Tappert's efforts to recover the score and parts from Bilse (without success)
-
-
B begins to revise the FS
B begins composition of the Volksfest finale
1st revision completed (1878 version)
B writes to Tappert; another unsuccessful attempt to recover score and parts from Bilse
B describes the revised version of his FS and announces his intention of replacing the Scherzo with a new "Hunt" Scherzo
"Hunt" Scherzo is composed
-
-
B begins to compose a 3rd version of the finale to replace the Volksfest finale
-
-
New finale is completed (1880 version)
-
-
1880 version premiered in Vienna by the VPO conducted by Richter; 1st premiere of a B symphony to be conducted by someone other than B
B makes some changes to the symphony after the first performance, resulting in the 1881 version
A performance of the 1881 version in Karlsruhe under Felix Mottl is a failure; 1st performance of a B symphony at which the composer is not present
-
-
B sends the score of the 1881 version to publishers Bote and Bock of Berlin with a view to publication, but it is rejected
-
-
B sends the score of the 1881 version to publishers Schott of Mainz with a view to publication, but it is again rejected
1st and 3rd movements of the 1881 version are performed at the Sondershausen Musikfest in Thuringia
B makes some further changes while preparing the score to be sent with Anton Seidl to New York, resulting in the 1886 version
B sends a copy of the score of the 1886 version to Anton Seidl, who takes it to New York
2nd version (1878–1886) of the symphony set aside by B
Hermann Levi sends a postcard to Viennese publisher Albert Gutmann interesting him in the publication of the FS
Gutmann agrees to publish the FS, but demands an advance fee of 1,000 marks (1,000 fl.)
B writes to Levi rejecting Gutmann's terms as impossible for him to meet
-
-
B relents and agrees to Gutmann's terms when it becomes clear that Levi will be able to raise the 1,000 fl. (does Gutmann reveives the 1,000 fl. now?)
B and his collaborators (Ferdinand Löwe, Franz Schalk and Joseph Schalk) begin to revise the FS for publication
Franz Scalk writes to his brother Joseph, telling him that Löwe has reorchestrated much of the FS with B's approval
1887 version completed (partially preserved in some surviving orchestral parts from the premiere)
A planned performance of 1887 version in Munich under Levi is cancelled due to the unavailability of orchestral parts
-
-
1887 version is premiered in Vienna by the Vienna Philharmonic under Hans Richter
The Stichvorlage (engraver’s copy of the 1887 version) is extensively revised in B's hand, completed and dated, resulting in the 1888 version
B writes to Franz Schalk: asks him to thank Löwe for list of differences between score used at premiere on 22 January 1888 and revised Stichvorlage
B sends Levi the Stichvorlage for a concert Levi was preparing to give in Munich on 14 April 1888 (the concert was cancelled when Levi fell ill)
and asks him to have the orchestral parts amended accordingly at his, B's, expense; attached to the Stichvorlage is Löwe's list of revisions
B writes to Levi: requests that the Stichvorlage and revised parts be sent to him (Levi actually had a new set of parts drawn up from scratch)
1886 version performed in New York under Anton Seidl
B signs the contract for the publication of the FS (does Gutmann receive his 1,000 fl. now?)
B writes to Arthur Nikisch: the Stichvorlage has been sent via Gutmann to the printers Engelmann & Mühlberg of Leipzig
-
-
Gutmann finally publishes the 1888 version of B's FS; this is the first printed edition of the work
-
-
Gutmann issues a corrected edition of the 1888 version
The 1888 version is performed in Munich under Franz Fischer (deputizing for the indisposed Hermann Levi)
Fischer writes to B: first rehearsal has had to be abandoned; the handwritten orchestral parts were defective and had to be revised by a local copyist
-
-
B writes to Levi, asking him to send Fischer's revised orchestral parts to Gutmann for printing
3 more performances of the 1888 version take place using Fischer's revised handwritten orchestral parts
-
-
Gutmann publishes the orchestral parts of the FS (1888 version) and another print of the full score
1st performance of the FS using Gutmann's printed orchestral parts takes place in Vienna under Joseph Schalk

Instrumentation

The symphony requires an instrumentation of one pair each of flutes, oboes, clarinets, bassoons, with four horns, three trumpets, three trombones, timpani and strings. From the 1878 revision onwards, a single bass tuba is also incorporated into the instrumentation. The published score of 1889 introduces a part for third flute (doubling on the piccolo) and a pair of cymbals.

Selected discography

The first commercial recording of part of the symphony was of the scherzo from the 1888 version, made by Clemens Krauss with the Vienna Philharmonic in 1929. The first commercial recording of the entire symphony was made by Karl Böhm with the Dresden Staatskapelle in 1936, in the Haas/1881 version.

The versions most often recorded are the Haas and Nowak editions of the 1880 score (referred to as the 1881 and 1886 versions in the list above). Any modern recording that does not specify this can be safely assumed to be one of these versions, while early LPs and CD remasterings of old recordings are usually of Ferdinand Löwe's 1888 edition (for example, those by Wilhelm Furtwängler and Hans Knappertsbusch).

Eliahu Inbal was the first to record the original 1874 version, edited by Leopold Nowak, with the Frankfurt Radio Symphony Orchestra. The recording is available on Teldec LPs and CDs. Robert Haas's edition of the 1878 version has never been recorded as a whole, although the Volksfest finale has been recorded individually, for example by Georg Tintner.

1889/90 first edition

Haas edition (1936, 1944), based on the 1881 manuscript

Nowak edition of 1953, based on the 1886 copy

Nowak edition of 1974, based on the 1874 manuscript

A digitalization of the concert can be heard on John Berky's Website: Symphony No. 4 (1874) by K. Woess, 20 September 1975

Nowak edition of the 1878 "Volksfest" finale, published 1981

Korstvedt edition (2004), based on the 1888 manuscript

See also

Notes

  1. Constantin Floros, as reported in Brown, A. Peter (2003). The second golden age of the Viennese symphony: Brahms, Bruckner, Dvořák, Mahler, and selected contemporaries. Bloomington, IN: Indiana University Press. p. 219. ISBN 0-253-33488-8.
  2. 1 2 3 4 5 Williamson, John (2004). "Programme symphony and absolute music". In Williamson, John. The Cambridge Companion to Bruckner. Cambridge Companions to Music. Cambridge University Press. p. 110. ISBN 0-521-00878-6.
  3. Deryck Cooke (1969) described this movement as "simply a recasting, in 1880, of the 1878 [sic] finale into its present form". Presumbably he meant "a recasting … of the 1874 finale...", which is much closer to the 1880 finale than is the Volksfest finale of 1878.
  4. 1 2 3 "Introduction, (Symphony No. 4)", from Bruckner, Anton (1990). Robert Haas, ed. Symphonies nos. 4 and 7 in full score. New York: Dover. p. xi. ISBN 0-486-26262-6.
  5. According to the New Grove Dictionary of Music and Musicians (ed. Stanley Sadie, 2001), the Stichvorlage is "lost". See Korstvedt (1996) for a description of this document.
  6. Mahler did cut and reorchestrate the symphony, but it was the 1888 version he altered.
  7. Benjamin Marcus Korstvedt (2004), p. 125
  8. Robert Simpson (1966), for example, whose critical estimation of the 1888 version was damning.
  9. Hans F. Redlich (1954), pp. v-vi.
  10. Hans F. Redlich (1954), p. vi.
  11. Cooke (1969), p. 364.
  12. Benjamin Marcus Korstvedt (2004), p. 129; Korstvedt (1996), p.21
  13. Bruckner/Korstvedt (2004)

Published editions of the symphony

References

External links

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