1) Wittmaach., K.: Uber die normale und pathologische Pneumatisation des Schlafenbeins entschleisslich ihrer Beziehungen su der Mittelohrkrankungen. Jena East Germany, Fischer, 1-64, 1918.
2) Proctor, B.: The development of the middle ear space and their surgical significance. J. Laryng. 78: 631-648, 1964.
3) Bast and Forester: Origin and distribution of air cells in the temporal bone. Arch. Otolaryngol., 30: 183-250, 1939.
4) Schwarzbart, A.: Repneumatization of the tympanic cavity in otosurgery. J. Laryng. 74: 541-551, 1960.