1. Increased sheep numbers and the loss of heather moorland in the Peak District, England;Anderson;Biol. Conserv.,1981
2. Heather condition and management in the uplands of England and Wales;Bardgett,1992
3. Landscape changes in Britain;Barr,1986
4. Production of maps and estimates of area;Bradbury,1989
5. ITE Land Classification: classification of all 1-km squares in Great Britain;Bunce,1991