MLA

Brodsky, Joseph, 1940-1996. Series II -- Writings -- Poetry -- Individual Poems -- Oblaka, Russian language version. Box 198, folder 4305. [1989]. https://collections.library.yale.edu/catalog/11702627.

APA, 6th edition

Brodsky, Joseph, 1940-1996. (["Box 198, folder 4305"])([1989])[Series II -- Writings -- Poetry -- Individual Poems -- Oblaka, Russian language version]. https://collections.library.yale.edu/catalog/11702627.