MLA

Thomson, Virgil, 1896-1989. [Sunflower] Sunflower / music by V.G. Thomson ; poem by William Blake.. Box 29A/41, folder 445. 1804-1990 (inclusive). https://collections.library.yale.edu/catalog/32304127.

APA, 6th edition

Thomson, Virgil, 1896-1989. (["Box 29A/41, folder 445"])(1804-1990 (inclusive))[[Sunflower] Sunflower / music by V.G. Thomson ; poem by William Blake.]. https://collections.library.yale.edu/catalog/32304127.