Underground Comix are known for using different prices, covers (art or color variations) and interior content to distinguish different printings.
1st print Summer (September ?) 1970 has 0.75 USD cover price with glasses attached to page 3.
2nd-3rd print have 1.00 USD cover price. Both say which printing. 3rd print glasses attached at centerfold.
Inside front cover introductory strip with indicia information at bottom of page.