Thomson, J Oliver
JM Dent & Sons , 1961
Buku Teks
edited by Edward Whiting Fox
Oxford University Press, 1957
Buku Teks
Rand McNally & Company, 1952
Buku Referensi
Shepperd, William R., author
Barnes and Noble, 1959
Buku Referensi
Sellman, Roger Raymond, author
Edward Arnold, 1954
Buku Referensi