jantawat, Somjate, Piya Duangpatra, Sorasith Vacharotayan, Wade W. McCall, and Wade W. McCall. “Preliminary Trials for the Response of Guatemala Corn to Sulfur and Trace Elements in Red Brown Earth Soil of Thailand1”. Agriculture and Natural Resources 6, no. 2 (July 1, 1966): 60–66. accessed August 28, 2026. https://li01.tci-thaijo.org/index.php/anres/article/view/240631.