Underground Comix are known for using different prices, covers (art or color variations) and/or interior content to distinguish between printings.
1st print April (actually May) 1972 has 0.50 USD cover price.
2nd print believed to be indistinguishable from 1st print.
3rd print October 1975 has 0.75 USD cover price and says 3rd edition on inside front cover.
4th print 1979(?) has 1.25 USD cover price and says New Revised Edition on cover.
Contents different from earlier printings?
This issue has variants: