1. Columbia University Rare Book & Manuscript Library, MS X893 Z8 v.2 no.4 DS ID: DS18578 Title: Letter and Hebrew text Author: Avraham Dov Place: Hungary Date: 1807.
2. Columbia University Rare Book & Manuscript Library, MS X893 Z8 v.2 no.4 DS ID: DS19520 Title: Letter and Hebrew text Author: Hirsh Kunrat Place: Germany Date: 1797.