Notes: • "First Sphere Books edition 1972" • "Reprinted 1973"; thus second printing, no number line • Month from amazon.uk • The cover says Clarke is the editor but not the title page which notes only "With a Foreword by Arthur C. Clarke", listing the three authors under the title • The Editor's Introduction is not credited or signed, whereas Clarke's Foreword is. • "Cover illustration by David A. Hardy" on back cover, no visible signature on the artwork • UK 35p, Canada 1.50c, Australia 1.10c, New Zealand 1.10c, East Africa 8/25