Originally published in paperback by Random House Children's Books, New York, in 1974 Originally published by Random House Children's books, New York, in 1992 Originally published in hardcover by Random House Children's Books in 2007 Originally published in paperback by Orion Children's Books, Hachette UK, London, in 2019. Originally published as Polar babies by Random House Children's Books, 2000. Originally published: New York : Random House Children's Books, 2019 Originally published in hardcover by Harcourt Children's Books, 1993 Originally published in paperback in London by Puffin Books in 2018. "Originally published in a slightly different form by Random House Children's Books, New York, in 1949"--Title page verso. "Originally published in a slightly different form by Random House Children's Books, New York, in 2000"--Copyright page