Natta Takrattanasaran, Jongruk Chanchareonsook, Suthep Thongpae, and Ed Sarobol, “Evaluation of Mehlich 3 and Ammonium Bicarbonate-DTPA Extractants for Prediction of Available Zinc in Calcareous Soils in Central Thailand”, Agr. Nat. Resour., vol. 44, no. 5, pp. 824–829, Oct. 2010.