Arias, P. R. (1997). Why upland farmers adopt conservation measures. Manila Bulletin.
Chicago Style aipamenaArias, Priscila R. "Why Upland Farmers Adopt Conservation Measures." Manila Bulletin 1997.
MLA aipamenaArias, Priscila R. "Why Upland Farmers Adopt Conservation Measures." Manila Bulletin, 1997.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.