@article{Hembars’ka_Zaderei_2016, title={Estimations of the integral of modulus for mixed derivatives of the sum of double trigonometric series}, volume={68}, url={https://umj.imath.kiev.ua/index.php/umj/article/view/1890}, abstractNote={For functions of two variables defined by trigonometric series with quasiconvex coefficients, we estimate their variations in the Hardy – Vitali sense.}, number={7}, journal={Ukrains’kyi Matematychnyi Zhurnal}, author={Hembars’ka, S. B. and Zaderei, P. V.}, year={2016}, month={Jul.}, pages={908-921} }