1. Renewable Energy Policy Network for the 21st Century. www.ren21.net
2. Popel’, O.S., Frid, S.E., Shcheglov, V.N., et al., Comparative analysis of structure indexes for solar collectors produced in Russia and abroad. New technical solutions, Teploenergetika, 2006, no. 3.
3. Rekomendatsii po tekhniko-ekonomicheskomu obosnovaniyu primeneniya netraditsionnykh solnechnykh i solnechno-teplonasosnykh sistem teplokhladosnabzheniya na grazhdanskikh i promyshlennykh ob”ektakh (Recommendations for Technical-Economical Grounding of Nontraditional Solar and Solar-Heat-Pumping Systems for Heat and Cold Supply at Civil and Industrial Objects), Moscow, 1987, p. 53.
4. Zakhidov, R.A., Anarbaev, A.I., Orlova, N.I., and Tadzhiev, U.A., Appl. Solar Energy, 2008, vol. 44, no. 2, p. 113.
5. Denisova, A.E., Mazurenko, A.S., Todortsev, Yu.K., and Dubkovskii, V.A., Soil energy in heat-pumping heliosystems for power supply, Ekotekhnol. Resursosberezh., 2000, no. 1, pp. 27–30.