Barnet, Sylvan
Longman, 2001
Buku Teks
Evans, B. Ifor
Penguin Books , 1948
Buku Teks
Rees, Leslie, 1905-2000
Angus & Robertson, 1973
Buku Teks
Quinn, Arthur Hobson
Irvington Publishers, 1943
Buku Teks
Krutch, Joseph Wood
George Braziller, 1957
Buku Teks