Heller, R. L. (1979). Earth science (2d ed.). Webster Division, McGraw-Hill.
Chicago-čujuhus (17. p.)Heller, Robert L. Earth Science. 2d ed. New York: Webster Division, McGraw-Hill, 1979.
MLA-čujuhus (9. p.)Heller, Robert L. Earth Science. 2d ed. Webster Division, McGraw-Hill, 1979.
Muitte dárkkistit čujuhemiid riektatvuođa, ovdal go geavahat daid iežat deavsttas.