EVALUASI VIRULENSI VIRUS TUNGRO DARI BEBERAPA DAERAH ENDEMI DAN UJI KETAHANAN PLASMANUTFAH PADI = EVALUATION OF TUNGRO VIRUS VIRULENCE FROM SOME ENDEMIC AREAS AND SCREENING RESISTANCE OF RICE GERMPLASM - Perpustakaan UGM, i-lib ([Yogyakarta] : Universitas Gadjah Mada, 2010)