Below is a list of websites that we use on a regular basis and that contain a wealth of substantive information:
Crop Circle Connector
Crop Circle Connector Archives (Subscription only)
Nancy Talbott, John Burke and Dr William Levengood’s research
Old Crop Circles by Terry Wilson
Crop Circle Centre by Bertold Zugelder
Lucy Pringle
UK Crop Circles by Dan Vidler and Chris Riley
The Croppie
Crop Circle Access – Crop Circle Visitor Centre
Temporary Temples by Karen Douglas and Steve Alexander
Crop Circles and More by Bert Janssen
German crop circle website by Andreas Müller
Dutch crop circle website by the late Janet Ossebaard
The Core Group Initiative by Paul Jacobs
Crop Circles / Sacred Sites by Ron Russell
South Oxfordshire Crop Circle Map by Dan Watt
The International Crop Circle Database by Paul Vigay (archived)
Oxfordshire CCCS (archived)
Crop Circles by Ellis C Taylor (archived)
Crop Circle University by Randell Sarneel
Crop Circle Research Archive 