Dropping in on Gottfried Leibniz (2013) (writings.stephenwolfram.com)

One thing I would like to read is the history of the House of Brunswick he was supposed to be writing for much of his career. According to another website: "In the end, Leibniz was never able to complete the history, although the three volumes of his history were eventually published after his death."

But I can't seem to find them anywhere in any form.