Kei, Ushimura
International House of Japan, 2003
Buku Teks
Johnson, Carol
Allen and Unwin, 1989
Buku Teks
Zainah Anwar
Yayasan Mohamed Noah; Petaling Jaya, Selangor, Malaysia , 2011
Buku Referensi
Bailey, Cyril
Oxford University Press, 1951
Buku Teks
edited by Val Moses
Grayson Publishing, 2007
Buku Teks SO