GNU Free Documentation License, version 1.1
['GNU Free Documentation License, version 1.2', 'The purpose of this License is to make a manual, textbook, or other functional and useful document "free" in the sense of freedom: to assure everyone the effective freedom to copy and redistribute it, with or without modifying it, either commercially or noncommercially. Secondarily, this License preserves for the author and publisher a way to get credit for their work, while not being considered responsible for modifications made by others.', 'GNU Free Documentation License, version 1.3', 'GNU Free Documentation License, version 1.1']