Cite

Insurance maps of Portsmouth, Virginia.

MLA

Company, Sanborn Map. Insurance Maps of Portsmouth, Virginia. Sanborn Map Company, 1920. https://collections.library.yale.edu/catalog/16387378.

APA, 6th edition

Company, S. M. (1920). Insurance maps of Portsmouth, Virginia. [Cadastral maps, Fire insurance maps]. Sanborn Map Company, https://collections.library.yale.edu/catalog/16387378.