Machan, C. M., P. K. Hrynchak, and E. L. Irving. “Dry Eye: Age-Related Prevalence, Correlation Between Symptoms and Diagnoses, and Significant Associations”. Canadian Journal of Optometry, vol. 81, no. 3, Sept. 2019, pp. 9-17, doi:10.15353/cjo.v81i3.408.