Shpak, Grygorii     Increasing of natural gas using efficiency in heating engineering aggregates [Текст] / Grygorii Shpak // Current issues of civil and environmental engineering : XII Intern. sci. conf., 17-19 Sept. 2009, Rzeszow, Poland : book of abstr. / Rzeszow univ. of technology. — Rzeszow, 2009. — P. 82.