The Public Library of Science initiative began with the circulation of the following open letter, urging publishers to allow the research reports that have appeared in their journals to be distributed freely by independent, online public libraries of science. (Google)
In any case somebody out there actually believes in the things David said so an open letter like this is necessary. (Google)
I have written an open letter on immigration reflecting the consensus opinion of economists on the major issues. In cooperation with the Independent Institute I am looking for as many signatures as possible from economists and other social scientists. (Google)