BBC Earth (Firm)
Lonely Planet, 2010
Buku Referensi
Kong, Seong Gyeong, author
Mimeumsa, 2004
Buku Teks
O`Neil, L. Peat, author
Writer's Digest Books, 1995
Buku Teks
Kaelany H.D., author
Midada Rahma Press, 2012
Buku Teks
Marzuki Usman, author
HL, 1999
Buku Teks