International Journal of Agriculture Sciences Volume-4 Issue-5
MARTINS J L, XAVIER D M, SILVA A S, et al. CHARACTERIZATION OF THE COAL HUMIC ACIDS FROM THE CANDIOTA COALFIELD, BRAZIL. International Journal of Agriculture Sciences. 2012; 4(5):238-242. http://dx.doi.org/10.9735/0975-3710.4.5.238-242