MLA

Johnston, William Walker Whitehall, 1835-1886. Album Page 42. Recto: Barracks for the 1st West India Regiment at Old Nassau Fort in Nassau, New Providence. Box 1, folder 40. circa 1860. https://collections.library.yale.edu/catalog/16657590.

APA, 6th edition

Johnston, William Walker Whitehall, 1835-1886. (["Box 1, folder 40"])(circa 1860)[Album Page 42. Recto: Barracks for the 1st West India Regiment at Old Nassau Fort in Nassau, New Providence]. https://collections.library.yale.edu/catalog/16657590.