editor, William Morris
Houghton Miffiln, 1976
Buku Referensi
Walters, Morgan L
N.Y.Holt Rinehart and Winston,inc, 1966
Buku Teks
Longman, 1984
Buku Referensi
edited by Henry Cecil
George Routledge & Sons, 1946
Buku Referensi
editor in chief John Sinclair
Collins, 1991
Buku Referensi