edited by Martin H. Manser
W & R Chambers, 1995
Buku Referensi
Nandy, Milon
Composite Study Aid Publications, 1993
Buku Referensi
edited by G. Elgie Christ
Frederick Warne and Co, 1960
Buku Referensi
G & C Merriam Co., 1951
Buku Referensi
Kim, Gwang-hae
Do Seo Chul pan Natmal, 2000
Buku Referensi