Alekseevskaya, M., A. Gabrielov, I. Gel’fand, A. Gvishiani, and E. Rantsman. “Formal Morphostructural Zoning of Mountain Territories”. Journal of Geophysics, Vol. 43, no. 1, May 1977, pp. 227-33, https://journal.geophysicsjournal.com/JofG/article/view/158.