1. Washburn, A. L. Geocryology: a survey of periglacial processes and environments. (Edward Arnold, london, 1980).
2. Muller, S. W. Permafrost or permanently frozen ground and related engineering problems. Strategic Eng. Study, Spec. Rep. 62, 136 pp., Off. Chief of Eng., Army. (Washington, D. C. U. S. Reprinted by Edwards, J. W. Ann Arbor, Mich., 231 pp., 1947).
3. Zhang, T., Barry, R. G., Knowles, K., Heginbottom, J. A. & Brown, J. Statistics and characteristics of permafrost and ground-ice distribution in the Northern Hemisphere1. Polar Geogr 23, 132–154, doi: 10.1080/10889379909377670 (1999).
4. Burn, C. R. & Smith, C. A. S. Observations of the “Thermal Offset” in Near-Surface Mean Annual Ground Temperatures at Several Sites near Mayo, Yukon Territory, Canada. Arctic 41, 99–104 (1988).
5. Wang, W. et al. Diagnostic and model dependent uncertainty of simulated Tibetan permafrost area. The Cryos Discuss 9, 1769–1810, doi: 10.5194/tcd-9-1769-2015 (2015).