SFBC Nelson Doubleday & Co. 1977. Set of 6 series comprising the complete Edgar Rice Burroughs Mars series. the first 5 books (A Princess of Mars, The Gods of Mars / The Warlord of Mars, Thuvia Maid of Mars / The Chessmen of Mars, The Mastermind of Mars / A Fighting Man of Mars, Swords of Mars / Synthetic Men of Mars) all have covers and interior illustrations by Frank Frazetta. The last book (Llana of Gathol / John Carter of Mars) has a cover and interior illustrations by Richard Corben. A very nice set, generally found worn.