APA
Vassilev S. V., Vassileva C. G. & Vassileva C. G.Comparative chemical and mineral characterization of some Bulgarian coals. : .
Chicago
Vassilev Stanislav V, Vassileva Christina G and Vassileva Christina G.Comparative chemical and mineral characterization of some Bulgarian coals. : .
Harvard
Vassilev S. V., Vassileva C. G. and Vassileva C. G.Comparative chemical and mineral characterization of some Bulgarian coals. : .
MLA
Vassilev Stanislav V, Vassileva Christina G and Vassileva Christina G.: . .
