Held, R. B., & Clawson, M. (1965). Soil conservation in perspective. Baltimore, Maryland: The Johns Hopkins Press.
Chicago Style aipamenaHeld, R. Burnell., và Marion Clawson. Soil Conservation in Perspective. Baltimore, Maryland: The Johns Hopkins Press, 1965.
MLA aipamenaHeld, R. Burnell., và Marion Clawson. Soil Conservation in Perspective. Baltimore, Maryland: The Johns Hopkins Press, 1965.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.