Gaya APA
Krevelen, D, W, V. (1981).
Coal Science and Technology 3: Coal Typology-Chemistry-Physics-Constitution .
Amsterdam:
Elsevier.
Gaya MLA
Krevelen, D., W., Van.
"Coal Science and Technology 3: Coal Typology-Chemistry-Physics-Constitution".
Amsterdam:
Elsevier,
1981.
Text.