S. U.  Patel, B. Kumar, J., Badhe, Y. P., Sharma, B. K., Saha, S., Biswas, S., Chaudhury, A., Tambe, S. S., and Kulkarni, B. D., ?Estimation of gross calorific value of coals using artificial neural networks?, Fuel, vol. 86, no. 3, pp. 334-344, 2007.