1. Andersen, I.;Camner, P.;Jenson, PL.: Philipson, K.;Proctol, D.F. (1974): Nasal clearance in monozygotic twins. American Review of Respiratory Diseases, 110: 301.
2. Bang, B.C.; Mukherjee, A. L; Bang, F. B. (1967): Human nasal mucus flow rates. The Johns Hopkins Medical Journal, 121:38.
3. Berg, O.H.; Bergstedt, C.; Carenfelt and Zind, M.G. (1981): Discrimination of purulent from non-purulent maxillary sinusitis: Clinical and Radiographic Diagnosis. Ann. Otol. Rhin, and Laryng., 90:272.
4. Evert, C. (1965): On the mucus flow rate in the human nose. Acta Otolaryngologica (supplement), 200(1): 61.
5. Fabricant, N.D. (1945): Scott Browns Diseases of the Ear, Nose and Throat (Eds. Ballantyne and Groves). London: Butterworths, 4th ed., Vol. 1, P. 166.