religion, language, art, and custom. J. Murray. 1920: 360. Clarke, Peter B., and PeterBeyer, eds. 2009. The World's Religions: Continuities and Transformations
University of California Press. 1996. ISBN 9780520204973. Trapp, Erich; Beyer, Hans-Veit; Walther, Rainer; Sturm-Schnabl, Katja; Kislinger, Ewald; Leontiadis