1. APHA-AWWA-WPCF 2540 D, 1989. Total suspended solid dried at 103–105°C.
2. APHA-AWWA-WPCF 2540 E, 1989. Fixed and volatile solid ignited at 550°C.
3. ASTM D2216, 1998. Standard test method for laboratory determination of water (moisture) content of soil and rock by mass.
4. ASTM D5373, 2002. Standard test methods for instrumental determination of carbon, hydrogen, and nitrogen in laboratory samples of coal and coke.
5. Seasonal variation of potentially mineralizable nitrogen in four cropping systems;Bonde;Soil Science Society of America,1987