S. Husodo and B. Bharoto, “WILLINGNESS TO PAY KONSUMEN TERHADAP PRODUK PERTANIAN ORGANIK (STUDI KASUS DI KODYA YOGYAKARTA) (THE CONSUMER’S WLLINGNESS TO PAY FOR ORGANIC PRODUCT)”, JIIP, vol. 5, no. 1, pp. 31–37, Jul. 2009.