H. F.  Lu, Cheng, C. G., Tang, X., and Hu, Z. H., ?FTIR spectrum of Hypericum and Triadenum with reference to their identification.?, Acta Bot. Sin., vol. 46, pp. 401-406, 2004.

F.  Kuginuki and Namba, T., ?Pharmacognostical studies on the folk medicine in Japan: 10. On "Otogiri-so". Anatomical features of leaves and stems of  Hypericum and Triadenum (Hypericaceae): 1.?, J. Jap. Bot., vol. 68, pp. 224-235 (1993) - illus., 1993.

T. S.  Cooperrider, ?The Clusiaceae (or Guttiferae) Ohio.?, Castanea, vol. 54, pp. 1-11 (1989) - map., 1989.