English: Cabinet Card of Dr. Paul Leverkühn (w:de:Paul Leverkühn), Dated 1898. (The back of the card states that he was a current member of the American Ornithologists Union. The handwritten abbreviations under his signature are M.D. (he was a doctor) and C.M.A.O.U. (Current Member of theAmerican Ornithologists Union). From the Ruthven Deane Collection of Portraits, Prints and Photographs Division, Library of Congress.17). This photo was located in the Ruthven Deane collection at the Library of Congress. Deane, an American ornithologist, was inspired to collect photographs of "bird men" because of Leverkühn's enormous collection of photos of ornithologists, which was sold after his death in 1905. See the following article for more details: T. S. Palmer, "The Deane Collection of Portraits of Ornithologists--the Development of an Idea," Science, n. s., 100, no. 2596 (1944): 288-290.