Gaya APA
CRELLING, J, C., Suarez, I. (2008).
Applied Coal Petrology "The Role of Petrology in Coal Utilization" .
Inggris:
Elsevier.
Gaya MLA
CRELLING, JOHN, C.., Suarez, Isabel.
"Applied Coal Petrology "The Role of Petrology in Coal Utilization"".
Inggris:
Elsevier,
2008.
Textbook.