Cita APA (7a ed.)

(1994). Project learning tree: Environmental education activity guide (2nd.). Project Learning Tree.

Cita Chicago Style (17a ed.)

Project Learning Tree: Environmental Education Activity Guide. 2nd. Washington: Project Learning Tree, 1994.

Cita MLA (9a ed.)

Project Learning Tree: Environmental Education Activity Guide. 2nd. Project Learning Tree, 1994.