Ostapenko, Olga, and Olena Bakum. 2015. “ECONOMIC EFFICIENCY OF HEAT-PUMPING STATIONS ON THE CONDITIONS OF FUEL AND ENERGY RESOURCES COST CHANGE AND VARIABLE OPERATION MODES”. Scientific Works of Vinnytsia National Technical University, no. 1 (November). https://works.vntu.edu.ua/index.php/works/article/view/406.