Underground Comix are known for using different prices, covers (art or color variations) and/or interior content to distinguish between printings.
1st print 1970 had 1.50 USD cover price and was a magazine sized fanzine self-published by Richard Corben.
2nd print 1970 (actually December 1971) has 0.50 USD cover price. This version is indexed here.
3rd-4th print have 0.50 USD cover price and are believed to be indistinguishable from 2nd print.
Inside front cover with introductory text and image with indicia information at bottom of page.
Illustration on inside back cover.