HUDSON, N. (1979). Soil conservation. Batsford.
Lua i Stíl Chicago (17ú heag.)HUDSON, Norman. Soil Conservation. London: Batsford, 1979.
Lua MLA (9ú heag.)HUDSON, Norman. Soil Conservation. Batsford, 1979.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.