Gaya APA

Petersen, M, S., Rigby, J, K. (1984). Interpreting earth history : a manual in historical geology . America: WM.C. Brown Company Publishers.

Gaya MLA

Petersen, Morris, S.., Rigby, J., Keith. "Interpreting earth history : a manual in historical geology". America: WM.C. Brown Company Publishers, 1984. Text.