MLA

Opper, Frederick Burr, 1857-1937. Postponing the operation .... 1899 January 11. https://collections.library.yale.edu/catalog/2057794.

APA, 6th edition

Opper, Frederick Burr, 1857-1937. (1899 January 11)[Postponing the operation ...]. https://collections.library.yale.edu/catalog/2057794.