1. Piersol G. A.: Human Anatomy. Ed. 7, Philadelphia, J. B. Lippincott Co., 1:192, 1919.
2. The Ethmoid Cells at Birth and Their Development during Fetal Life
3. Schaeffer J. P.: The Nose and Olfactory Organ. Philadelphia, P. Blakiston's Son & Co., p. 214, 1920.
4. Turner A. L.: Diseases of the Nose, Throat and Ear. New York, William Wood & Co., p. 17, 1924.
5. CASE REPORTS