Q. Al-Abachi, Mouyed, et al. “Spectrophotometric Determination of Procaine Hydrochloride in Pharmaceutical Preparations Via Oxidative Coupling Reaction”. Tikrit Journal of Pharmaceutical Sciences, vol. 9, no. 2, Apr. 2023, pp. 213-22, doi:10.25130/tjphs.2013.9.2.3.213.222.