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2. Moses RA. Adler’s Physiology of the Eye. St. Louis, CV Mosby, 1981, 7th Ed., pp 21–22.
3. Tear physiology and dry eyes;Holly;Surv Ophthalmol,1977
4. Exploring the sting;Josephson;J Am Optom Assoc,1987
5. The pH question and some answer;Carney;Contact Lens Spect,1986