BARTLETT, Roger. Her Imperial Majesty's Director and Curator of the Mennonite Colonies in Russia: Three Letters of Georg Trappe. Journal of Mennonite Studies, [S.l.], v. 12, p. 45-64, jan. 1994. ISSN 08245053. Available at: <http://jms.uwinnipeg.ca/index.php/jms/article/view/411>. Date accessed: 16 oct. 2018.