[1]Л. М. Ушивец, "Учет экологического фактора в цене сланца", PMI, т. 90, сс. 63-65, май 1981.

[1]L. M. Ushivets, "Accounting of the Ecological Factor in the Price of Oil Shale", PMI, vol. 90, pp. 63-65, May 1981.