Ashton-Jones, N. J. (2000). A guide to understanding the environment. National Integrated Protected Areas Programme, Protected Areas and Wildlife Bureau.
Chicago-referens (17:e uppl.)Ashton-Jones, Nick J. A Guide to Understanding the Environment. Quezon City: National Integrated Protected Areas Programme, Protected Areas and Wildlife Bureau, 2000.
MLA-referens (9:e uppl.)Ashton-Jones, Nick J. A Guide to Understanding the Environment. National Integrated Protected Areas Programme, Protected Areas and Wildlife Bureau, 2000.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.