Johann Peter Frank. - Letter, Notes and books Dr. Isidore William Held [friend Albert Einstein] - 1831-1831

Original letter addressed to Dr. Isidore William Held, accompanied by the books and a document containing notes. The letter answers Dr. Held’s question about helminthology. The connection between a gastroenterologist (his medical specialty) and helminthology—the study of parasitic worms—is direct and clinically relevant.

The letter and the documents containing notes also discuss Johann Peter Frank, the author of the books *Pathologie und Therapie*.

Dr. Isidor William Held was a prominent and influential American physician, medical author, and Jewish community leader in New York City. He lived from May 15, 1876, to March 2, 1947.
During his career, he became widely known for his expertise in gastroenterology and his tireless efforts to rescue Jewish medical refugees from Nazi Germany.
Although he was primarily known as a gastroenterologist and general practitioner, his scientific expertise extended broadly across internal medicine.