When I started my library career, way back in the eighties, the hardest working books in the library where the encyclopedias. Even in a small library the encyclopedias would become discolored through use and would be replaced every year or so. The publishers would update the books using dozens of editors and hundreds of experts.
In the past few years the use of print encyclopedias has fallen dramatically. But, at the same time, the on line encyclopedia called Wikipedia has become one of the top ten web sites. What is interesting about Wikipedia is that all of the articles are generated by anyone who wishes to spend the time and effort to write one. Though this method is unorthodox, compared to traditional encyclopedias, it has produced a pretty effective encyclopedia. The Washington Post article Death by Wikipedia: The Kenneth Lay Chronicles illustrates some of the issues using Wikipedia, especially for controversial information.