"William Bertram", obituary, Variety, May 9, 1933, page 62. Internet Archive. Retrieved October 5, 2018.
"Film Flashes", news item about Bertram's work on The Idol, Variety, September 10, 1915, p. 20, col. 2. Internet Archive. Retrieved October 13, 2018.
familysearch.org
William ultimately had six siblings: five brothers and a sister. "Canada Births and Baptisms, 1661-1959", Walkerton, Bruce, Ontario, 1880. FamilySearch, archives, The Church of Jesus Christ of Latter-day Saints, Salt Lake City, Utah. Retrieved October 5, 2018.
"Twelfth Census of the United States: 1900", digital copy of original enumeration page, Switzer family, Chelan Precinct, Washington, June 15, 1900. FamilySearch, census records, archives of The Church of Jesus Christ of Latter-day Saints, Salt Lake City, Utah. Retrieved October 6, 2018.
"Marie Osborne", filmography, Turner Classic Movies (TCM), Turner Broadcasting System, a subsidiary of Time Warner, Inc., New York, N.Y. Retrieved October 6, 2018.
"William Bertram", partial filmography as both actor and director, TCM. Retrieved October 6, 2018.