Bennett. (1955). Elements of soil conservation (2.). Mc Graw Hill Book company.
Dyfyniad Arddull ChicagoBennett. Elements of Soil Conservation. 2. NewYork: Mc Graw Hill Book company, 1955.
Dyfyniad MLABennett. Elements of Soil Conservation. 2. Mc Graw Hill Book company, 1955.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.