Butter, B. (1980). Soil classification for soil survey. Clarendon Press.
Chicago Style aipamenaButter, B.E. Soil Classification for Soil Survey. Oxford: Clarendon Press, 1980.
MLA aipamenaButter, B.E. Soil Classification for Soil Survey. Clarendon Press, 1980.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.