I see that Hard Hitting Songs for Hard-Hit People has been reissued. It was compiled by Alan Lomax, Woody Guthrie, and Pete Seeger, and first published by Oak Publications in 1967. You'll find a list of the 165 songs in this book here (click). If you're interested in the songs of the activists in the U.S. in the first half of the twentieth century, you need this book.
-Joe Offer-