Alfred Richard Orage
Wikipedia's biography of his life.
http://en.wikipedia.org/wiki/Alfred_Richard_Orage
Anderson, Margaret C.
Archives finding aid. Letters, photos and manuscripts.
http://www.uwm.edu/Library/arch/findaids/uwmmss12.htm
Fritz Peters
Dedicated to Fritz Peters (1913-1979), he is most well known for his memoirs covering his early years living at G. I. Gurdjieff's Institute for the Harmonious Development of Man.
http://www.fritzpeters.info/
Jean Toomer
Wikipedia's biography of his life.
http://en.wikipedia.org/wiki/Jean_Toomer
Jeanne de Salzmann
Wikipedia's biography of her life.
http://en.wikipedia.org/wiki/Jeanne_de_Salzmann
John G. Bennett
Wikipedia's biography of his life.
http://en.wikipedia.org/wiki/John_G._Bennett
Margaret Caroline Anderson
Wikipedia's biography of her life.
http://en.wikipedia.org/wiki/Margaret_Caroline_Anderson
The Thomas de Hartmann Papers
Documents de Hartmann's life and work through musical sketches, manuscript scores, and printed music and contains materials relating to G.I. Gurdjieff.
http://webtext.library.yale.edu/xml2html/music/ht-d.htm
Thomas and Olga de Hartmann
Wikipedia's very short biography of the Thomas and Olga de Hartmann
http://en.wikipedia.org/wiki/Thomas_and_Olga_de_Hartmann