Evan E. Bolton, Yanli Wang, Paul A. Thiessen, Stephen H. Bryant (2008). „Chapter 12 PubChem: Integrated Platform of Small Molecules and Biological Activities”. Annual Reports in Computational Chemistry4: 217-241. DOI:10.1016/S1574-1400(08)00012-1.
Kiers C. T., De Boer J. L., Olthof R., Spek A. L. (1976). „The crystal structure of a 2,2-diphenyl-1-picrylhydrazyl (DPPH) modification”. Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry32: 2297. DOI:10.1107/S0567740876007632.