Old downtown San Francisco [California] : historic sites & buildings / History Maps, Ken Cathcart.
MLA
Cathcart, Ken G. Old Downtown San Francisco [California] : Historic Sites & Buildings / History Maps, Ken Cathcart. [Ken Cathcart?], 0AD. https://collections.library.yale.edu/catalog/15818745.
APA, 6th edition
Cathcart, K. G. (0 C.E.). Old downtown San Francisco [California] : historic sites & buildings / History Maps, Ken Cathcart. [Maps]. [Ken Cathcart?], https://collections.library.yale.edu/catalog/15818745.