| Name | Info | Provider | Link |
|---|---|---|---|
| Vitamin C | free resource | MedlinePlus Health Information | https://medlineplus.gov/vitaminc.html |
| subscription/membership/fee required | Ovid Technologies, Inc. | http://ovidsp.ovid.com/ovidweb.cgi?T=JS&PAGE=linkout&SEARCH=16076019.ui | |
| subscription/membership/fee required | Springer | https://www.springerlink.com/openurl.asp?genre=article&issn=0364-3190&volume=30&issue=4&spage=479 |