1st print November 1969 has 1.00 USD cover price. Has blue (may fade to green with age) cover with white paper stock.
2nd print August 1971 has 0.50 USD cover price. Has red cover with newsprint paper stock. Price is solid black. Says Second Edition.
3rd - 4th prints have 0.50 USD cover price. Price just outlined in black. No copyright symbol on inside front cover. Says Second Edition.