MLA

Kern, Edward Meyer, 1823-1863. Palette leaf and Paul Weber's landscape palette, 2 sheets removed from 1850 notebook. Box 1, folder 6. n.d.. https://collections.library.yale.edu/catalog/16101257.

APA, 6th edition

Kern, Edward Meyer, 1823-1863. (["Box 1, folder 6"])(n.d.)[Palette leaf and Paul Weber's landscape palette, 2 sheets removed from 1850 notebook]. https://collections.library.yale.edu/catalog/16101257.