Frey, W. H.; DeSota-Johnson, D.; Hoffman, C.; McCall, J. T. (October 1981). "Effect of stimulus on the chemical composition of human tears". American Journal of Ophthalmology. 92 (4): 559–567. doi:10.1016/0002-9394(81)90651-6. ISSN0002-9394. PMID7294117.
Frey, William H.; Desota-Johnson, Denise; Hoffman, Carrie; McCall, John T. (October 1981). "Effect of Stimulus on the Chemical Composition of Human Tears". American Journal of Ophthalmology. 92 (4): 559–567. doi:10.1016/0002-9394(81)90651-6. PMID7294117.
Frey, W. H.; DeSota-Johnson, D.; Hoffman, C.; McCall, J. T. (October 1981). "Effect of stimulus on the chemical composition of human tears". American Journal of Ophthalmology. 92 (4): 559–567. doi:10.1016/0002-9394(81)90651-6. ISSN0002-9394. PMID7294117.
Frey, William H.; Desota-Johnson, Denise; Hoffman, Carrie; McCall, John T. (October 1981). "Effect of Stimulus on the Chemical Composition of Human Tears". American Journal of Ophthalmology. 92 (4): 559–567. doi:10.1016/0002-9394(81)90651-6. PMID7294117.
Frey, W. H.; DeSota-Johnson, D.; Hoffman, C.; McCall, J. T. (October 1981). "Effect of stimulus on the chemical composition of human tears". American Journal of Ophthalmology. 92 (4): 559–567. doi:10.1016/0002-9394(81)90651-6. ISSN0002-9394. PMID7294117.