De Smith, S.A. (Stanley A.), author
Penguin Education, 1973
Buku Teks
Thompson, Brian
Blackstone press , 1997
Buku Teks
Robson, William Alexander, 1895-1980, author
Stevens & Sons Limited, 1951
Buku Teks
Phillips, O. Hood
Swett and Maxwell, 1973
Buku Teks
Phillips, O. Hood
Sweet & Maxwell, 1987
Buku Teks