The Rise and Fall of California's Radical Prison Movement - Eric Cummins - Google Books

https://books.google.de/books?id=QXpejAPTqH0C&pg=PA215&dq=%22United+Prisoners+Union%22#v=onepage

This is a history of the California prison movement from 1950 to 1980, focusing on the San Francisco Bay Area's San Quentin State Prison and highlighting the role that prison reading and writing played in the creation of radical inmate ideology in…