@article{Raşa_1985, title={Approximation of twice differentiable functions by positive linear operators}, volume={14}, url={https://ictp.acad.ro/jnaat/journal/article/view/1985-vol14-no2-art6}, abstractNote={Not available.}, number={2}, journal={Anal. Numér. Théor. Approx.}, author={Raşa, I.}, year={1985}, month={Aug.}, pages={131–135} }