Gaya APA
Hargrove, E, C. (1989).
Foundations of environmental ethics. .
Englewood Cliffs:
Englewood Cliffs Prentice-Hall.
Gaya MLA
Hargrove, Eugene, C..
"Foundations of environmental ethics. ".
Englewood Cliffs:
Englewood Cliffs Prentice-Hall,
1989.
Buku.