Oskar Hainauer began collecting in earnest in order to furnish his home on the Rauchstrasse in Berlin, which he had built in 1874. Beginning with a small collection of modern paintings, he expanded to include decorative arts. Inspired by the great residences of the Paris Rothschilds, he sought to emulate the quality of such collections. He was acquainted with the Parisian collector Frédéric Spitzer, and bought at the major auctions including the Beurnonville, Ganay and Graham sales as well as Spitzer's own posthumous sale in 1893. After Hainauer's death in 1894, his wife Julie arranged to have his collection catalogued, and in 1897 this catalogue was published, written by Wilhelm von Bode. In 1906 the dealer Joseph Duveen (Duveen Brothers, Inc.) bought the entire Hainauer collection, which was subsequently dispersed.
Bode, Wilhelm von, ed. Die Die Sammlung Oscar Hainauer / The Collection of Oscar Hainauer. [bound as one volume, English and German pages interleaved in one page sequence] Berlin, 1897 and London, 1906: 1-7.
American Art News IV (14 July 1906):1
Kuhrau, Sven. Der Kunstsammler im Kaiserreich: Kunst und Repräsentation in der Berliner Privatsammlerkultur. Kiel, 2005:39-45, 275.