This image was acquired from
wikimedia. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
Keywords from Image Description:
Correspondence Heiden Friedrich and Engelmann George Feb BHL. Correspondence Heiden Friedrich and Engelmann George Feb Text Illustration Heiden to Engelmann biodiversitylibrary org Heiden Friedr von der Permission to digitize granted by rights holder Biodiversity Heritage Library Check categories October PDold books