http://www.ex.ac.uk/~cnfrench/ics/cbru/monitor/natnat.htm

http://www.ddgi.es/espais/iserpaig.htm

http://www.fotonatura.com/portfolio/jvarkel.htm

http://www.ringelnatter.net/english.htm

http://www.1freespace.com/mitjaderenda/Snakes/Natnat.html

http://www.bnhof.de/~rattau/natrix.htm

Snakes and Lizards

Snakes of the World

Snakes – A Natural History

Mammals, Reptiles and

Amphibians of Britain and Europe

Tom Langton

Chris Mattison

Roland Bauchot

Paul Morrison

Whittet Books

Blandford

Sterling

Macmillan