European Jazz and Close Harmony Vocal Groups - A substantial part of this site is devoted to the Comedian Harmonists. Also has information on some other groups of the 1930s. - http://www.yodaslair.com/dumboozle/eurojazz/eurodex.html
The Web's Resources for the Comedian Harmonists - History of the group and its successors, profiles of the members, photos, lyrics, sound clips. In German and English. - http://www.comedian-harmonists.com/
IMDb: Comedian Harmonists - Films in which the group performed. - http://www.imdb.com/name/nm0363575/