MLA-style Citation Format:

Photographer last name, first name, middle initial. "Title of photograph." Date. Title of Collection. [Protocol and address] [digital ID] (date of visit).

O'Sullivan, Timothy H. "Incidents of war." 1865. Selected Civil War Photographs from the Library of Congress, 1861-1865. [http://memory.loc.gov/ammem/cwphtml/cwphome.html] [cwp4a40875 40875] (August 14, 1996).

Turabian-style Citation Format:

Photographer last name, first name, middle initial. Date. Title of photograph. In Collection. [Type of medium] Available Protocol: Protocol/Site/Path/File; digital ID. [Access date].

O'Sullivan, Timothy H. 1865. Incidents of war. In Selected Civil War Photographs from the Library of Congress, 1861-1865. [Online] Available http://memory.loc.gov/ammem/cwphtml/cwphome.html; [cwp4a40875 40875]. [August 14, 1996].