Fu, Ying, et al. “Synthesis, Characterization and Crystal Structure of 4-Dichloroacetyl-2,5-Dimethyl-8-Oxo-1,4-diazabicyclo[3.3.0]octane”. Asian Journal of Chemistry, vol. 26, no. 10, May 2014, pp. 2896-8, doi:10.14233/ajchem.2014.15959.