Question: Who bought one of the Van Gogh series Sunflowers in 1905?
About the article "Sunflowers (Van Gogh series)", section "Provenances".

Candidate passages:
Two Paris versions Van Gogh exchanged with Gauguin in December 1887 or January 1888 were both sold to Ambroise Vollard: one in January 1895 and the other in April 1896.
The first canvas resided for a short time with Félix Roux, but was reacquired by Vollard and sold to Degas from his estate to Rosenberg, then to Hahnloser and bequested to the Kunstmuseum in Bern.
The second was acquired by the Dutch collector Hoogendijk at the sale of his collection by Kann, who ceded the painting to Richard Bühler and then via Thannhauser to the Metropolitan Museum in New York.
Two of Van Gogh's "Sunflowers" paintings never left the artist's estate: the study for one of the Paris versions (F.377) and the repetition of fourth version (F.458).
Both are in the possession of the Vincent van Gogh Foundation, established 1962 by Vincent Willem van Gogh, the artist's nephew, and on permanent loan to the Van Gogh Museum, Amsterdam.
Five other versions are recorded in the Van Gogh estate papers:
the final Paris version (F.452) in the artist's estate was sold 1909 via C. M. van Gogh, The Hague (J. H. de Bois) to Kröller-Müller
(F.457) sold 1894 to Emile Schuffenecker.
(Tokyo version).
(F.456) sold 1905 via Paul Cassirer to Hugo von Tschudi.
(Munich version).
(F.459) sold 1908 C. M. van Gogh (J. H. de Bois), The Hague to Fritz Meyer-Fierz, Zürich (destroyed Japan 1945).
(F.454) sold 1924 via Ernest Brown & Phillips (The Leicester Gallery) to the Tate Gallery; since on permanent loan to the National Gallery, London.
(London version).
Two Arles versions left the artist's estate unrecorded:
(F.453) (private collection).
Sold 1891 to Octave Mirbeau, Paris, (via Tanguy, Paris) for £12 (about £1,300 in 2013 £).
Sold 1996 to a private collector for an undisclosed sum.
(F.455) (Philadelphia version).
Sunflowers (original title, in French: Tournesols) are the subject of two series of still life paintings by the Dutch painter Vincent van Gogh.
The earlier series executed in Paris in 1887 depicts the flowers lying on the ground, while the second set executed a year later in Arles shows bouquets of sunflowers in a vase.
In the artist's mind both sets were linked by the name of his friend Paul Gauguin, who acquired two of the Paris versions.
About eight months later Van Gogh hoped to welcome and to impress Gauguin again with "Sunflowers", now part of the painted "décoration" that he prepared for the guestroom of his "Yellow House," where Gauguin was supposed to stay in Arles.
After Gauguin's departure, Van Gogh imagined the two major versions as wings of the "Berceuse Triptych", and finally he included them in his exhibit at Les XX in Bruxelles. 
"Now that I hope to live with Gauguin in a studio of our own, I want to make decorations for the studio.
Nothing but big flowers.
"See Letter 527Leaving aside the first two versions, all Arlesian "Sunflowers" are painted on size 30 canvases. 
Little is known of Van Gogh's activities during the two years he lived with his brother Theo in Paris, 1886-1888.
The fact that he had painted Sunflowers already is only revealed in spring 1889, when Gauguin claimed one of the Arles versions in exchange for studies he had left behind after leaving Arles for Paris.
Van Gogh was upset and replied that Gauguin had absolutely no right to make this request: "I am definitely keeping my sunflowers in question.
He has two of them already, let that hold him.
And if he is not satisfied with the exchange he has made with me, he can take back his little Martinique canvas, and his self-portrait sent me from Brittany, at the same time giving me back both my portrait and the two sunflower canvases which he has taken to Paris.
So if he ever broaches this subject again, I've told you just how matters stand.
"The two Sunflowers in question show two buttons each; one of them was preceded by a small study, and a fourth large canvas combines both compositions.
These were Van Gogh's first paintings with ""nothing but sunflowers""—yet, he had already included sunflowers in still life and landscape earlier. 
"Two Cut Sunflowers" (F375) is one of a sequence of four paintings that Van Gogh made in the summer of 1887.
The first (Van Gogh Museum, F377) was a preparatory sketch.
Paul Gauguin had the second and third "Two Cut Sunflower" paintings (F375, F376) and hung them proudly in his Paris apartment above his bed.
In the mid-1890s he sold them to fund his trip to the South Seas.
The image of the four sunflowers was made on a large canvas.