-. (1991). Proceedings the twentieth annual convention. Ikatan Ahli Geologi Indonesia.
Chicago Style aipamena-. Proceedings the Twentieth Annual Convention. Ikatan Ahli Geologi Indonesia, 1991.
MLA aipamena-. Proceedings the Twentieth Annual Convention. Ikatan Ahli Geologi Indonesia, 1991.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.