Name Info Provider Link
subscription/membership/fee required Atypon https://journals.sagepub.com/doi/10.1258/ijsa.2010.010281?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub 0pubmed
Syphilis free resource MedlinePlus Health Information https://medlineplus.gov/syphilis.html