Gunther, John. Inside Europe. New York, Harper & Brothers, 1940. с. 21.
Payne, Robert. The Life and Death of Adolf Hitler. New York, Praeger, 1973. с. 12. The marriage took place early in the morning, and Klara is said to have complained: 'We were married at six o'clock in the morning, and my husband was already at work at seven.'