Pat Delgado and Colin Andrews produced their Circles Phenomenon Research (CPR) newsletter which later became Circle Lines (CPD) for several years from 1990 onwards:
April 1991
July 1991
October 1991
January 1992
April 1992
July 1992
CPR / CPD Newsletter
April 1991
July 1991
October 1991
January 1992
April 1992
July 1992
Crop Circle Research Archive 