MLA

Trudeau, G. B., 1948-. Doonesbury. Box 1981. 1981 June 18. https://collections.library.yale.edu/catalog/2052828.

APA, 6th edition

Trudeau, G. B., 1948-. (["Box 1981"])(1981 June 18)[Doonesbury]. https://collections.library.yale.edu/catalog/2052828.