Ward, A.C.
Longman, 1955
Buku Teks
Stephen, Leslie, 1832-1904
University Paperbacks, 1963
Buku Teks
Richetti, John
John Wiley & Sons, 2017
Buku Teks
Stauffer, Donald Alfred
Princeton University Press, 1941
Buku Teks
Crosland, Margaret
Constable, 1981
Buku Teks