Lokhande, Pradeep, et al. “A Novel and Efficient Approach for the Synthesis of New Halo Substituted 2-arylpyrazolo[4,3-C] Coumarin Derivatives”. European Journal of Chemistry, vol. 2, no. 2, June 2011, pp. 223-8, doi:10.5155/eurjchem.2.2.223-228.336.