Zhao1, Yuhao, et al. “Highly Efficient Zinc Oxide Nanoparticles Catalyzed Green Synthesis of 1,5-Benzodiazepines under Solvent-Free Path”. Asian Journal of Chemistry, vol. 26, no. 24, Dec. 2014, pp. 8539-42, doi:10.14233/ajchem.2014.18319.