Cita APA (7th ed.)
(1984). Focus on earth science (teachers annoted ed.). Charles E. M.
Cita Chicago (17th ed.)
Focus on Earth Science. teachers annoted ed. Ohio: Charles E. M, 1984.
Cita MLA (9th ed.)
Focus on Earth Science. teachers annoted ed. Charles E. M, 1984.
Atenció: Aquestes cites poden no estar 100% correctes.