Balamurugan, N., et al. “Molecular Structure, Vibrational Spectra, Theoretical NBO and HOMO-LUMO Analysis of Bi-Glycine Hydrobromide by DFT Method”. Asian Journal of Chemistry, vol. 26, no. 14, July 2014, pp. 4259-65, doi:10.14233/ajchem.2014.16093.