APA (7e ed.) Bronvermelding

Ravenholt, A. (1968). Philippine Rock Industries, Incorporated: Grinding rock becomes a successful business venture. American Universities Field Staff.

Chicago (17e ed.) Bronvermelding

Ravenholt, Albert. Philippine Rock Industries, Incorporated: Grinding Rock Becomes a Successful Business Venture. [New York]: American Universities Field Staff, 1968.

MLA (9e ed.) Bronvermelding

Ravenholt, Albert. Philippine Rock Industries, Incorporated: Grinding Rock Becomes a Successful Business Venture. American Universities Field Staff, 1968.