On his personal copy of A Summary View, which was published anonymously, Jefferson wrote, “by Thomas Jefferson.”
Other fun Jefferson stuff from the 2020 book, Author in Chief by Craig Fehrman
Handy Sized Books

[Thomas Jefferson] bought octavo-sized volumes that fit his hands, what he called “books of a handy size.” Books, after all, were tools.
“Sometimes, one of Jefferson’s slaves remembered, “he would have twenty of them down on the floor at once.”