Arias, P. R. (1997). Why upland farmers adopt conservation measures. Manila Bulletin.
Lua i Stíl Chicago (17ú heag.)Arias, Priscila R. "Why Upland Farmers Adopt Conservation Measures." Manila Bulletin 1997.
Lua MLA (9ú heag.)Arias, Priscila R. "Why Upland Farmers Adopt Conservation Measures." Manila Bulletin, 1997.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.