Originally published in hardcover by Harcourt Children's Books, 1993 Originally published in hardcover: Harcourt Children's Books, 2005 Originally published in hardcover by Random House Children's Books in 2007 Originally published in hardcover: New York : Clarion Books, 1998 Originally published in hardcover: New York : Random House Children's Books, 2010 Originally published in hardcover in 2016 by Chronicle Books, LLC. Originally published: London : Macmillan Children's Books, 1999 Originally published: New York : Dutton Children's Books, 1992 Originally published as Polar babies by Random House Children's Books, 2000. Originally published by Macmillan Childrens Books, 1977.