Published in Penguin Books 1949 Reprinted 1950, 1952, 1954, 1957, 1959, 1961, 1962, 1963, 1965, 1966, 1968, 1969, 1970, 1971, 1972, 1973, 1974, 1975 (twice), 1976, 1977 The cover shows an engraving by Cecil Keeling
Published in Penguin Books 1949 Reprinted 1950, 1952, 1954, 1957, 1959, 1961, 1962, 1963, 1965, 1966, 1968, 1969, 1970, 1971, 1972, 1973, 1974, 1975 (twice), 1976, 1977 The cover shows an engraving by Cecil Keeling