This is a new, neat tool that helps you find whether certain US published books are out of copyright even if they are published after 1923. As most copyright savvy people know, there was a period of time after that in which copyrights had to be officially renewed to stay valid, meaning that a lot of works published after that time are officially in the public domain in the United States. But these are hard to find, since renewal notices are hard to peruse and in many cases not machine-searchable at all. But no longer! Stanford has created a Copyright Renewal Database, making it quite easy to check if any book published first in the U.S. between 1923 and 1963 are in the public domain. It could potentially clear up copyright ambiguities for certain things taken from these works. http://collections.stanford.edu/copyrightrenewals/ FF