Melios, C. B., Delsin, A. M., Tognolli, J. O. and Molina, M. (1981) “Protonation constants of p-substituted benzylidenepyruvic acids”, Eclética Química, 6(1), pp. 51–54. doi: 10.26850/1678-4618eqj.v6.1.1981.p51-54.