Ghosh, A., S. Mondal, K. Islam, K. Mal, D. Bhattacharyya, and A. Bandyopadhyay. “Study of Three Level Cascade System: A Complete Analytical Approach”. Journal of Atomic, Molecular, Condensed Matter and Nano Physics, vol. 3, no. 2, Aug. 2016, pp. 97-104, doi:10.26713/jamcnp.v3i2.483.