They Called Him Father Gus, by Reverend Roy Bauer
Father Augustine Tolton, the First Black Priest in the United States, by the Pontifical Mission Societies
(Most links to publisher sites)
Augustus Tolton: The Church Is the True Liberator, by Joyce Duriga N.B.: This is the best available book.
Father Augustus Tolton: A Brief Biography of a Faithful Priest and Former Slave, by Joseph Perry [Amazon link; published by The Tolton Guild]
From Slave to Priest: The Inspirational Story of Father Augustine Tolton (1854-1897), by Sr. Caroline Hemesath, O.S.F.
Father Augustus Tolton: The Slave Who Became the First African-American Priest, by Deacon Harodl Burke-Sivers
Father Augustus Tolton: The First Recognized Black Priest in America, by Corinna Laughlin and Maria Laughlin