Kulshrestha, Avidha, et al. “Knoevenagel Condensation Shadowed by Michael Addition & O-Alkylation of Resorcinol, Malononitrile and Benzadehyde to Form Pyrrolidine, Piperidine and Morpholine Substituted Benzopyran Derivatives in Dry K2CO3”. Asian Journal of Chemistry, vol. 31, no. 7, June 2019, pp. 1470-2, doi:10.14233/ajchem.2019.21901.