APA (7th ed.) Citation

Earth Works Group (Estados Unidos) & Earth Works Group. (1990). 50 simple things kids can do to save the earth. Andrews and McMeel.

Chicago Style (17th ed.) Citation

Earth Works Group (Estados Unidos) and Earth Works Group. 50 Simple Things Kids Can Do to Save the Earth. Kansas City: Andrews and McMeel, 1990.

MLA (9th ed.) Citation

Earth Works Group (Estados Unidos) and Earth Works Group. 50 Simple Things Kids Can Do to Save the Earth. Andrews and McMeel, 1990.