Milroy, Patrick
Ward Lock Book, 1994
Buku Referensi
Sheard, Rod
Spon Press, 2001
Buku Teks SO
Shead, Rod
Spon Press, 2001
Buku Teks SO
edited by Christopher M. Perrins and Alex L.A. Middleton
Grolier International, 1993
Buku Referensi
edited by P.V. Vidyasagar
Mittal Publications, 2000
Buku Referensi