MLA

Riker, William E., 1873-1969. Certificate of membership in the Perfect Christian Divine Way : founded in San Francisco, Cal., 1908, by W.E. Riker. 191-?]. https://collections.library.yale.edu/catalog/31912831.

APA, 6th edition

Riker, William E., 1873-1969. (191-?])[Certificate of membership in the Perfect Christian Divine Way : founded in San Francisco, Cal., 1908, by W.E. Riker]. https://collections.library.yale.edu/catalog/31912831.