A. A. Tsagelnikova, Y. S. Boyarina, and O. V. Tsiganov, “THE STUDY OF MENTAL STATES TENNIS PLAYERS OF VARYING QUALIFICATIONS DURING THE COMPETITION”, Mod. Psych., vol. 2, no. 3 (5), pp. 227–232, Sep. 2019, doi: 10.46991/SBMP/2019.2.2(5).227.