Kamber, Victor (2003). Poison Politics: Are Negative Campaigns Destroying Democracy?; Basic Books, New York City; ISBN978-0-7382-0872-5. See p.270: "As Hubert Humphrey III, son of HHH and now Minnesota's attorney general, said...."
Solberg, Carl (1984). Hubert Humphrey: A Biography; Borealis Books, St. Paul MN; ISBN0-87351-473-4. See p.234: "In the summer of 1963... Hubert H. Humphrey III was also traveling to Europe... In August, Humphrey wrote his son's old headmaster: 'Skip has returned from Europe and believe it or not, he has married a very lovely young lady here in Virginia – Nancy Lee Jeffery. They were married in Europe so they could enjoy a little honeymoon there. We are very happy at the whole situation.'"...