References
- Portmann M., Claverie G. Rev. Laryng 1958; 79: 306
- Shea J. J. Ann. Otol., Rhinol. and Laryng 1958; 67: 932
- Roedi L. Pract. Oto-Rhino-Laryng 1960; 22: 410
- Taselaar M. thesis, Groningen University. 1959
- Van Gils J. J. P. thesis, Groningen University. 1962