Houghton Mifflin Harcourt Journeys "Triangle Square books for young readers." Houghton Mifflin Harcourt Publishing Company, Houghton Mifflin Harcourt Publishing Companyeditor Houghton Mifflin Harcourt Publishing Companyceditor Houghton Mifflin Harcourt Publishing Company Houghton Mifflin Books for children "A Doubleday book for young readers." Encyclopedia of birds for young readers