Gaya APA
Annval editions : environment 2000/2001. (2000).
Guilford:
Dushkin/ Mcgraw-Hill.
Gaya Chicago
Annval editions : environment 2000/2001.
19th..
Guilford:
Dushkin/ Mcgraw-Hill,
2000.
Buku.
Gaya MLA
Annval editions : environment 2000/2001.
19th..
Guilford:
Dushkin/ Mcgraw-Hill,
2000.
Buku.
Gaya Turabian
Annval editions : environment 2000/2001.
Guilford:
Dushkin/ Mcgraw-Hill,
2000.
Buku.