Srinivasa Rao, Chunduru, et al. “Decarboxylative Aromatization of B-Carbolines by Using Metal Free Catalysis and Efficient Synthesis of B-Carboline Derivatives”. Asian Journal of Chemistry, vol. 27, no. 12, Aug. 2015, pp. 4701-2, doi:10.14233/ajchem.2015.19254.