APA (7e ed.) Bronvermelding

Herrera, A. (1999). Highly active absorbent for SO2 removal prepared from coal ash (Part 3). Philippine Engineering Journal.

Chicago (17e ed.) Bronvermelding

Herrera, A.B. "Highly Active Absorbent for SO2 Removal Prepared from Coal Ash (Part 3)." Philippine Engineering Journal 1999.

MLA (9e ed.) Bronvermelding

Herrera, A.B. "Highly Active Absorbent for SO2 Removal Prepared from Coal Ash (Part 3)." Philippine Engineering Journal, 1999.