Gaya APA

Unsworth, J, F. (1991). Coal Science and Technology 19 : Coal Quality and Combustion Ferformance an International Perspective . New York: Elsevier Science Publ. B.V..

Gaya MLA

Unsworth, John, F.. "Coal Science and Technology 19 : Coal Quality and Combustion Ferformance an International Perspective". New York: Elsevier Science Publ. B.V., 1991. Text.