Halli, M.B., et al. “Synthesis, Characterization and Thermal Decomposition Studies of Biologically Active Mixed Ligand Complexes Derived from Benzofuran-2-Carboxylic Acid (2-Oxo-1,2-Dihydro-Indol-3-Yidene) Hydrazide and Acetylacetone, 1,10-Phenanthroline and 2,2’-Bipyridyl”. Asian Journal of Chemistry, vol. 23, no. 1, Sept. 2010, pp. 189-94, https://asianpubs.org/index.php/ajchem/article/view/10117.