Rajachandrasekhar, V., et al. “Synthesis of N-(3,4,10,10a-Tetrahydro-2H-1,9-Dioxa-4a-Azaphenanthrene- 6-yl)alkyl and Aryl Sulfonamides”. Asian Journal of Chemistry, vol. 26, no. 16, Aug. 2014, pp. 5263-7, doi:10.14233/ajchem.2014.17017.