| Name | Info | Provider | Link |
|---|---|---|---|
| subscription/membership/fee required | Ovid Technologies, Inc. | http://ovidsp.ovid.com/ovidweb.cgi?T=JS&PAGE=linkout&SEARCH=28565173.ui | |
| subscription/membership/fee required | Silverchair Information Systems | https://academic.oup.com/evolut/article-lookup/doi/10.1111/j.1558-5646.1999.tb05350.x |