| Name | Info | Provider | Link |
|---|---|---|---|
| Endoscopy | free resource | MedlinePlus Health Information | https://medlineplus.gov/endoscopy.html |
| subscription/membership/fee required | Ovid Technologies, Inc. | http://ovidsp.ovid.com/ovidweb.cgi?T=JS&PAGE=linkout&SEARCH=18685898.ui | |
| subscription/membership/fee required | Springer | https://dx.doi.org/10.1245/s10434-008-0012-1 |