Haeberli Wilfried et Vonder Muhll Daniel, On the characteristics and possible origins of ice in rock glacier permafrost, Zeitschrift fur Geomorphologie. Supplementband Zeitschrift fur Geomorphologie. Supplement;Zeitschrift fur Geomorphologie. Supplementary issue Annals of geomorphology. Supplement;Annales de geomorphologie. Supplement, 104, 1996, pp. 43-57