Zoning of the Territory of Russia According to the Efficiency of the Use of Low-Grade Ground Heat for HeatingG.P. Vasilyev, N.V. Peskov, V.F. Gornov, M.V. Kolesova and I.А. YurchenkoMATEC Web of Conferences, 30 (2015) 05003DOI: https://doi.org/10.1051/matecconf/20153005003