| Name | Info | Provider | Link |
|---|---|---|---|
| subscription/membership/fee required | Elsevier Science | https://linkinghub.elsevier.com/retrieve/pii/S0939-6411(04)00194-8 | |
| Tears | free resource | MedlinePlus Health Information | https://medlineplus.gov/tears.html |
| subscription/membership/fee required | Ovid Technologies, Inc. | http://ovidsp.ovid.com/ovidweb.cgi?T=JS&PAGE=linkout&SEARCH=15567301.ui |