Copyleft is a method of making a program, software, literature or works of people free to be modified by other people, but not with the intention of reproducing, adapting or distributing for commercial purposes.
How To Identify Copyleft Sources
- Works produced by organizations other than the United States Federal Government may be protected by U.S. and international copyright laws.
- Confirm the absence of the copyright symbol, the name of the Copyright holder, and the statement "All Rights Reserved". Take note that not all copyright materials are marked this way because they are not required by law to do so.
- Confirm the presence of Creative Commons, ShareAlike or GNU Free Documentation licenses at the bottom of the pages.
List of Copyleft Sources
The following list suggests web resources that may have some copyleft information or media. This does not necessarily indicate that all the content on the provided websites is copyleft. To avoid copyright infringement, please ensure that the information or media you are using is licensed under Creative Commons, Public Domain, Share-Alike, or GNU Free Documentation. If in doubt, please contact your deputy editor-in-chief for help.
- National Library of Medicine – MedlinePlus - 
- National Cancer Institute – Physician Data Query PDQ® 
- Libre Pathology - 
- Radiopaedia.org - 
- Centers for Disease Control and Prevention (CDC) - 
- SurgWiki - 
- Surveillance, Epidemiology, and End Results (SEER) - 
- Ganfyd - Get A Note From Your Doctor - 
- Wikipedia - 
- National Eye Institute - 
- National Institute of Diabetes and Digestive and Kidney Diseases - 
- National Human Genome Research Institute - 
- National Institute of Allergy and Infectious Diseases - 
- National Heart, Lung and Blood Institute - 
- National Institute of Mental Health - 
- National Institute of Neurological Disorders and Stroke - 
- WikiBooks - 
- ECG learning center - 
- All the material from these website should be referenced, with a link to the source page.
Journals and Search Engines
- PLOS.org - 
- BioMed Central - 
- Springer Open - 
- Wiley - 
- Creative Commons Search - 
List of Medical Wikis in English
The following is a list of medical wikis in english. "Wiki" does not necessarily signify copyleft information. To avoid copyright infringement, please ensure that the information or media you are using is licensed under Creative Commons, Public Domain, Share-Alike, or GNU Free Documentation. If in doubt, please contact your deputy editor-in-chief for help.
- Basic Physics of Digital Radiography Wikibook
- Basic Physics of Nuclear Medicine
- Biomedical Cybernetics Wikia
- Blepharitis FAQ Wikibook
- Cardiology and Cardiothoracic Surgery
- Complementary and Alternative Medicine (CAM) Encyclopedia
- Clinical Informatics Wiki
- Sexual Health Wikibook
- Stress-related Disorders Wikibook
- Surgical Procedures Wikibook