Cite

Lady Irvin from a picture in Mr. Harding ['s collection?]. [art original]

MLA

Harding, G. P. (George Perfect), 1780-1853, artist. Lady Irvin from a picture in Mr. Harding ['s collection?]. [art original]. [not after 1806]. https://collections.library.yale.edu/catalog/16193665.

APA, 6th edition

Harding, G. P. (George Perfect), 1780-1853, artist. ([not after 1806])[Lady Irvin from a picture in Mr. Harding ['s collection?]. [art original]]. https://collections.library.yale.edu/catalog/16193665.