Kumar, B., P. Paurush, S. K. Sharma, and G. S. Prasad Singh. “Assessment of Coal Pillar Stability Using Principal Component Analysis and Stepwise Selection and Elimination”. Journal of Mines, Metals and Fuels, vol. 69, no. 3, May 2021, pp. 81-87, doi:10.18311/jmmf/2021/27783.