Wageninggen, & International Soil reference and Information Centre. (1990). Annual report 1990. The Netherland: International Soil reference and Information Centre Wageninggen.
Dyfyniad Arddull ChicagoWageninggen, và International Soil reference and Information Centre. Annual Report 1990. The Netherland: International Soil reference and Information Centre Wageninggen, 1990.
Dyfyniad MLAWageninggen, và International Soil reference and Information Centre. Annual Report 1990. The Netherland: International Soil reference and Information Centre Wageninggen, 1990.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.