| Name | Info | Provider | Link |
|---|---|---|---|
| Tears | free resource | MedlinePlus Health Information | https://medlineplus.gov/tears.html |
| subscription/membership/fee required | BioOne | https://doi.org/10.7589/0090-3558-37.2.387 | |
| subscription/membership/fee required | Silverchair Information Systems | https://meridian.allenpress.com/jwd/article-lookup/doi/10.7589/0090-3558-37.2.387 |