1. Avellis, G.: Arch. Laryng. Rhinol.1906, 458.
2. Berg, J. v. d.: Dissertation Groningen 1953.
3. —: Fol. phoniatr., Basel6, 8 (1954);7, 57 (1955).
4. Husson, R., u.A. Djian: J. Radiol. et Electrol.33, 127 (1952).
5. Luchsinger, R.: Fol. phoniatr., Basel5, 58 (1953).