Earl Spencer, brother of the late Princess Diana, said researching his family's history gave him the strength to survive the loss of his sister.
"You draw strength when you go back to your roots," he said Monday on CNN's "Larry King Live."
His research went into a new book, "The Spencers: A Personal History of an English Family." Spencer said it does not cover Diana's life, but is instead the history of "an aristocratic family."
"I don't really want to cash in on that," Spencer said of the life and death of his sister.