Hu, Q.-S. et al. 2016. DFT Studies of Synthesis of (4R,5S,8as)-4,5,8a-Triphenylhexahydropyrimido[4,5-d]pyrimidine-2,7(1H,3H)-dione. Asian Journal of Chemistry. 28, 6 (Feb. 2016), 1244–1252. DOI:https://doi.org/10.14233/ajchem.2016.19641.