LITERATURE
- Christensen , L. 1973 . Planteavl og geologi: Geologisk tolkning af afgrodemonstre i landbrugsjorder. . Det Nye Dansk Landbrug , 4 : 13 – 18 . 6
- Christensen , L. 1974 . Crop-marks revealing large-scale patterned ground structures in cultivated areas, southwestern Jutland, Denmark . Boreas , 3 : 153 – 180 .
- Christensen , L. 1978 . Waterstress conditions in cereals used in recognizing fossil ice-wedge polygonal patterns in Denmark and northern Germany. . Third Internat. Conf. on Permafrost, proceedings vol. , 1 : 255 – 261 .
- Svensson , H. 1963 . Some observations in West Jutland of a polygonal pattern in the ground . Geogr. Tidsskr. , 62 : 122 – 124 .
- Svensson , H. 1972 . The use of stress situations in vegetation for detecting ground conditions on aerial photographs. . Photogrammetria , 28 : 75 – 87 .
- Washburn , A. L. 1973 . Periglacial Processes and Environments. 320 London : E. Arnold .