Istendael, Geert van
Atlas, 1996
Buku Teks
Gullander, Ake
The Iowa State College Press, 1951
Buku Teks
Backman, Louise
Almqvist and Wiksell International, 1978
Buku Teks
Karimah Sausan, author
2015
UI - Makalah dan Kertas Kerja
Perry, James W.
Wadsworth, 1996
Buku Referensi