Z. A. Sizova, A. A. Karasyov, L. L. Lukackaya, and A. O. Doroshenko, “Acid-base and spectral properties of 3 (benzothiazolyl-2)cumarins and their imino analogs”, Khark. Univ. Bull. Chem. Ser., no. 26, pp. 26-38, May 2016.