| Name | Info | Provider | Link |
|---|---|---|---|
| Vitamin A | free resource | MedlinePlus Health Information | https://medlineplus.gov/vitamina.html |
| subscription/membership/fee required | Ovid Technologies, Inc. | http://ovidsp.ovid.com/ovidweb.cgi?T=JS&PAGE=linkout&SEARCH=33167034.ui | |
| subscription/membership/fee required | Silverchair Information Systems | https://academic.oup.com/rheumatology/article-lookup/doi/10.1093/rheumatology/keaa622 |