Yulianto, Gunawan. “PERSEPSI PETANI TERHADAP PENGEMBANGAN KEDELAI HITAM DI PLAYEN 133 - 144 GUNUNG KIDUL”. Jurnal Ilmu-Ilmu Pertanian, vol. 1, no. 2, Dec. 2005, pp. 133-44, https://jiip.polbangtanyoma.ac.id/index.php/jiip/article/view/276.