Doctor's Guide to the Internet www.pslgroup.com/DOCGUIDE.HTM - designed to help physicians harness the resources of the Internet.   Healthfinder www.healthfinder.org - links to hundreds of health publications and Internet health sites.   Healthgate www.healthgate.com - to make information access and coverage both thorough and easy, while maintaining the highest standards of academic and scientific integrity.   LOCATORplus www.nlm.nih.gov/locatorplus - the National Library of Medicine's catalog of books, journals, and audiovisuals and access points to other medical research tools.   National Institutes of Health www.nih.gov - information and research on disease detection and prevention.   National Library of Medicine www.nlm.nih.gov - the world's largest biomedical library, every significant program of the NLM is represented.