Avon Books, 1966. Mass Market Paperback. 3 books in slipcase. 4.25 x 7 inches each. Foundation (1966) 200 pages. Second Foundation (1964) 191 pages. Foundation and Empire (1966) 224 pages. All three: spine slightly cocked, bend in spine, red foredge. Slipcase has light/moderate wear, particularly bottom edge. Good+ condition...