Ambika, V.R. et al. 2017. Physio-Chemical Properties of Piperazinediium bis(4-Nitrophenolate)dihydrate: A Non-linear Optical Crystal. Asian Journal of Chemistry. 29, 9 (Jul. 2017), 2025–2030. DOI:https://doi.org/10.14233/ajchem.2017.20745.