This issue has variants.
Underground Comix are known for using different prices, covers (art or color variations) and/or interior content to distinguish between printings.
1st print March 1972 - 3rd print have 0.50 USD cover price. Believed to be indistinguishable from each other.
4th print has 0.75 USD cover price.
Image on inside of front cover with indicia information.
Advertisement for comix from Last Gasp Eco-Funnies on inside of back cover.