BLUEBIRD BOOKS. (2001). CHILDREN'S REFERENCE: THE UNIVERSE. BLUEBIRD BOOKS.
Chicago-viite (17. p.)BLUEBIRD BOOKS. CHILDREN'S REFERENCE: THE UNIVERSE. NEW DELHI: BLUEBIRD BOOKS, 2001.
MLA-viite (9. p.)BLUEBIRD BOOKS. CHILDREN'S REFERENCE: THE UNIVERSE. BLUEBIRD BOOKS, 2001.
Varoitus: Nämä viitteet eivät aina ole täysin luotettavia.