Hernandez-Ramirez, Raquel Eunice, et al. “Synthesis of Porphyrins As Precursors to PAMAM Dendrimers and Their Metal Chelating Properties”. European Journal of Chemistry, vol. 7, no. 1, Mar. 2016, pp. 49-55, doi:10.5155/eurjchem.7.1.49-55.1352.