KAISER, Darrel Philip. Origin & Ancestors Families Karle & Kaiser of the German-Russian Volga Colonies. [s.l.]: Lulu.com 551 s. Dostupné online. ISBN978-1-4116-9894-9. S. 59. (anglicky)
Encyclopedia Americana [online]. Americana Corporation, 1966 [cit. 2021-06-09]. Dostupné online. (anglicky)
MEAGHER, James Luke. The Great Cathedrals and Most Celebrated Churches of the World: Giving Their Founders, Patrons, Builders, and Architects, with a Complete History of Each Up to Our Times; Also, a Description of Their Different Styles of Architecture, and the Sculptures, Paintings, Ornaments, and Ceremonies of These Wonderful Temples of Christendom. [s.l.]: Russell Brothers Dostupné online. (anglicky)
Sigebert II. [online]. [cit. 2021-06-09]. Dostupné online. (anglicky)
OMAN, Charles. The Dark Ages, 476-918 [online]. Rivingtons, 1908 [cit. 2021-06-09]. Dostupné online. (anglicky)
