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 - 5th print are all 0.50 USD cover price.
1st print February (actually May) 1971 has ad for Thrilling Murder Comics on inside front cover.
2nd print has ad for "Posters by R. Crumb" added to inside front cover.
3rd print has "Eric Fromm has a 3-Foot Long One" on inside front cover.
4th print has matte cover? 5th print has glossy cover? Both have Apex Novelties poster ad on inside of front cover.
6th print has 0.75 USD cover price with "Apex Treasury of Underground Comics" on inside front cover.
7th print has 0.75 USD cover price with "Classics in their own time" ad on inside front cover.
in The Complete Crumb Comics (Fantagraphics, 1987 series) #7 - Hot 'n' Heavy (November 1991)Inside front cover ad that differs in later printings.
in Feite Freddy og vennene hans (Futurum Forlag, 1971 series) #4 (november 1973)
in R. Crumb's Carload o' Comics (Bélier Press, 1976 series) #[nn] (1976)
in The Complete Crumb Comics (Fantagraphics, 1987 series) #7 - Hot 'n' Heavy (November 1991)
in R. Crumb's Carload O'Comics (Bélier Press, Inc.; Kitchen Sink Press, Inc., 1996 series) #[nn] (1996)"Dedicated to my good ol' Uncle Pete"
in The Complete Crumb Comics (Fantagraphics, 1987 series) #7 - Hot 'n' Heavy (November 1991)
in The Book of Mr. Natural (Fantagraphics, 1995 series) #[nn] (September 1995)
in The Book of Mr. Natural (Fantagraphics, 2010 series) #[nn] (April 2010)
in The Complete Crumb Comics (Fantagraphics, 1987 series) #7 - Hot 'n' Heavy (November 1991)Image on back cover of issue.