Jenks, Edward
John Murray, 1933
Buku Teks
Bix, Brian H., author
Sweet & Maxwell, 1999
Buku Teks
Sinha, Surya Prakash, author
West Pub. Co., 1993
Buku Teks
Davies, Howard, author
Butterworth, 1991
Buku Teks
Hall, Jerome, author
Oceana Publication, 1958
Buku Teks