APA ציטוט

-. (1991). Proceedings the twentieth annual convention. Ikatan Ahli Geologi Indonesia.

Chicago Style (17th ed.) Citation

-. Proceedings the Twentieth Annual Convention. Ikatan Ahli Geologi Indonesia, 1991.

ציטוט MLA

-. Proceedings the Twentieth Annual Convention. Ikatan Ahli Geologi Indonesia, 1991.