APA

Halpern M., . (2001). Changes all Around us. Washington: National Geographic Society.

Chicago

Halpern Monica, . 2001. Changes all Around us. Washington: National Geographic Society.

Harvard

Halpern M., . (2001). Changes all Around us. Washington: National Geographic Society.

MLA

Halpern Monica, . Changes all Around us. Washington: National Geographic Society. 2001.