Robert E. Deppe compiled a book in the 1980s called "The House of Deppe." It details the genealogy of the Deppe family from Lippe (In modern-day Germany).
Grant Brunner has input every person from the book into Geni. Also, he has added information about his specific branch. As time goes on, the Deppe family will hopefully be further up to date with the help of the Geni community.
If there are any questions about the contents of the book, Grant Brunner can answer them. He is attempting to source as much as possible with excerpts from the book.