Rāingān Kānprachum thāng Wichākān Kasētsāt, khrang thī 6, Sākhā Sētthasāt Kasēt, na Mahāwitthayālai Kasētsāt, 30 Makarākhom - 2 Kumphāphan 2510 = The proceedings of the Sixth National Conference on Agricultural Sciences, Agricultural Economics at Kasetsart University, Bangkhen, Bangkok, January 30 - February 2, 1967