APA

Johnson، Trent, . (2001). What Color Is The Sky?. Washington: National Geographic Society.

Chicago

Johnson، Trent, . 2001. What Color Is The Sky?. Washington: National Geographic Society.

Harvard

Johnson، Trent, . (2001). What Color Is The Sky?. Washington: National Geographic Society.

MLA

Johnson، Trent, . What Color Is The Sky?. Washington: National Geographic Society. 2001.