1. Conant Norman F., Rosebury Theodor: Bacterial and Mycotic Infections of Man, Edited by Dubos Rene J., Philadelphia, J. B. Lippincott Co., 1948, p. 579.
2. Eggston Andrew A., Wolff Dorothy: Histopathology of the Ear, Nose and Throat, Baltimore, The Williams & Wilkins Co., 1947, p. 911.
3. Zinsser's Textbook of Bacteriology, Smith and Martin, Ed. 9, New York, Appleton-Century-Crofts, Inc., 1948, p. 830.