1. Das System Erde;Bolle;Geogr. Rundsch.,1993
2. Thermokarst in Siberia and its Influence on the development of lowland relief;Czudek;Quat. Res.,1970
3. Periglacial Geomorphology;Embleton,1975
4. That sinking feeling;Farley;Geogr. Mag.,1991
5. Das CO2-Klima-Problem;Flohn;Geogr. Rundsch.,1983