Tater, P.C., Aryamitra Pandey, and K.P. Soni. 2010. “Electronic Spectral Studies on Pr3+ Doped Sulphonanilide System, Part II&Dagger”;. Asian Journal of Chemistry 13 (2):577-80. https://asianpubs.org/index.php/ajchem/article/view/22634.