↑ At least one copy of every American film is required to be deposited and catalogued at the Library of Congress for copyright reasons. Although U.S. copyright law required copies to be deposited at the time of copyright registration, the Librarian of Congress was not required to retain those copies. "Under the provisions of the act of March 4, 1909, authority is granted for the return to the claimant of copyright of such copyright deposits as are not required by the Library." Report of the Register of Copyrights for the Fiscal Year 1912–1913, Library of Congress, 1913, p. 141.
↑ Dave Kehr (October 14, 2010). "Film Riches, Cleaned Up for Posterity". New York Times. Dicapai 2010-10-15. It’s bad enough, to cite a common estimate, that 90 percent of all American silent films and 50 percent of American sound films made before 1950 appear to have vanished forever.
