Cite

Letts's map of London [cartographic material].

MLA

Letts, Son, and author Co. Letts's Map of London [Cartographic Material]. Published by Letts, Son & Co., London Bridge, E.C., 0AD. https://collections.library.yale.edu/catalog/15286755.

APA, 6th edition

Letts, S., & Co., author. (0 C.E.). Letts's map of London [cartographic material]. [Maps]. Published by Letts, Son & Co., London Bridge, E.C., https://collections.library.yale.edu/catalog/15286755.