(1993)
Geothermal Energy. Technology. Ecology : 1993 Course, Text-Book Guideline,
Blagoevgrad: , 480 p. : ill.
(1993).
Geothermal Energy. Technology. Ecology : 1993 Course, Text-Book Guideline. Prossedings of the International Summer School on Direct Application of Geothermal Energy. Blagoevgrad: 480 p. : ill..