Classification systems used in the Library.
Photograph classification,
by Ethel A. Pennell; Book classification, by Lucie E. Wallace.

APA Citation

Metropolitan Museum of Art (New York, N. Library., Wallace, L. E., Pennell, E. A. (19111912). Classification systems used in the Library: Photograph classification. New York: [The Gilliss Press].

MLA Citation

Metropolitan Museum of Art (New York, N.Y.). Library, Lucie E Wallace, and Ethel A Pennell. Classification Systems Used In the Library: Photograph Classification. New York: [The Gilliss Press], 19111912.

Warning: These citations may not always be complete (especially for serials).