MLA

Trudeau, G. B., 1948-. Doonesbury. Box 1980. 1980 September 20. https://collections.library.yale.edu/catalog/2052824.

APA, 6th edition

Trudeau, G. B., 1948-. (["Box 1980"])(1980 September 20)[Doonesbury]. https://collections.library.yale.edu/catalog/2052824.