In My Opinion: An Inquiry into the Contemporary Novel (1952)
The Five Dollar Gold Piece: The Development of a Point of View (1956)
Undying Past (1961)
A Father Reads to His Children: An Anthology of Prose and Poetry (1965)
Princes of the Renaissance: A Chronicle of the Private Lives and Public Careers of the Kings, Dukes, Popes and Despots Who Ruled Italy in the Fifteenth Century (1969)
History as Literature (1971)
Lords of Italy: Portraits from the Middle Ages (1972)
Mid-Century: An Anthology of Distinguished Contemporary American Short Stories (1973)