Gaya APA
Annual editions: Environment 2002/2003. (2002).
GHuilford:
McGraw-Hill.
Gaya Chicago
Annual editions: Environment 2002/2003.
21th.
GHuilford:
McGraw-Hill,
2002.
Buku.
Gaya MLA
Annual editions: Environment 2002/2003.
21th.
GHuilford:
McGraw-Hill,
2002.
Buku.
Gaya Turabian
Annual editions: Environment 2002/2003.
GHuilford:
McGraw-Hill,
2002.
Buku.