Sakorn Phongpan. 1987. Studies on some chemical aspects of nitrogen and phosphorus in relation to the fertility of lowland paddy soils in the central plain of Thailand. , University of Tokyo;

Sakorn Phongpan. Studies on some chemical aspects of nitrogen and phosphorus in relation to the fertility of lowland paddy soils in the central plain of Thailand. . Tokyo:University of Tokyo, 1987.

Sakorn Phongpan. (1987) Studies on some chemical aspects of nitrogen and phosphorus in relation to the fertility of lowland paddy soils in the central plain of Thailand . University of Tokyo/Tokyo.