Cite

Triangle Letter Series No. 3 (with three stamps) (edition varieé)

MLA

Van Horn, Erica. Triangle Letter Series No. 3 (with Three Stamps) (Edition Varieé). 1978. https://collections.library.yale.edu/catalog/2056697.

APA, 6th edition

Van Horn, E. (1978). Triangle Letter Series No. 3 (with three stamps) (edition varieé). https://collections.library.yale.edu/catalog/2056697.