Winfield, P.H.
Sweet & Maxwell, Limited, 1948
Buku Teks
Keir, David Lindsay
Oxford University Press, 1948
Buku Teks
Dine, Janet
Blackstone Press, 1993
Buku Teks
Keir, David Lindsay
Oxford, 1959
Buku Teks
Dine, Janet
Blackstone Press, 1998
Buku Referensi