Small Gods Author:Terry Pratchett This is listed with ISBN 0-06-109217-7 on the back cover but has a blue cover with a green turtle. It is a full edition, mass-market sized paperback (standard-sized paperback). It's in very good shape.
Lost in the chill deeps of space between galaxies, it sails on forever, a flat, circular world carried on the back of a giant turtle - Discworld