APA (7th ed.) Citation

United States. National Park Service. (1990). Biological diversity makes a world of difference: A curriculum for teachers and interpreters. [publisher not identified].

Chicago Style (17th ed.) Citation

United States. National Park Service. Biological Diversity Makes a World of Difference: A Curriculum for Teachers and Interpreters. [Washington, D.C.]: [publisher not identified], 1990.

MLA (9th ed.) Citation

United States. National Park Service. Biological Diversity Makes a World of Difference: A Curriculum for Teachers and Interpreters. [publisher not identified], 1990.