| Name | Info | Provider | Link |
|---|---|---|---|
| Pain | free resource | MedlinePlus Health Information | https://medlineplus.gov/pain.html |
| free resource | PubMed Central | https://www.ncbi.nlm.nih.gov/pmc/articles/pmid/30753091/ | |
| free resource | Europe PubMed Central | https://europepmc.org/abstract/MED/30753091 | |
| free resource | Silverchair Information Systems | https://meridian.allenpress.com/angle-orthodontist/article-lookup/doi/10.2319/080518-570.1 |