Bratenko, M. K., M. M. Barus, and M. V. Vovk. “Esters of 4-Formylpyrazol-3-Carboxylic Acids”. Journal of Organic and Pharmaceutical Chemistry, vol. 15, no. 4(60), Dec. 2017, pp. 3-20, doi:10.24959/ophcj.17.925.