Z:gnu-www-ja-copyright-versus-community-2000--6eccb6-Look, for example, at the GNU/en

Look, for example, at the GNU free documentation license, which is used to make a book free. It allows anyone to make and sell copies of a modified version, but it requires giving credit in certain ways to the original authors and publishers in a way that can give them a commercial advantage and thus I believe make it possible to have commercial publishing of free textbooks, and if this works people are just beginning to try it commercially. The Free Software Foundation has been selling lots of copies of various free books for almost fifteen years now and it's been successful for us. At this point though, commercial publishers are just beginning to try this particular approach, but I think that even for functional works where the freedom to publish modified works is essential, some kind of compromise copyright system can be worked out, which permits everyone that freedom.