The Miriam and Ira D. Wallach Division of Art, Prints and Photographs: Art & Architecture Collection, The New York Public Library. "II Jahrgang (Liefr. III) Bl. 9. [Nine designs for jewelry, including necklace with pendant in shape of lock.]" The New York Public Library Digital Collections. 1872 - 1873. https://digitalcollections.nypl.org/items/510d47e3-04dd-a3d9-e040-e00a18064a99