I. V. Ukrainets, O. V. Mospanova, and T. V. Alexeeva, “The structure and biological properties of (4-hydroxy-1-methyl-2-oxo-1,2-dihydro-quinolin-3-yl)acetic acid and its esters”, J. Org. Pharm. Chem., vol. 11, no. 3(43), pp. 51–55, Sep. 2013.