@article{10_4064_sm180_2_4,
     author = {Z. Ditzian and S. Tikhonov},
     title = {Moduli of smoothness of functions and their derivatives},
     journal = {Studia Mathematica},
     pages = {143--160},
     publisher = {mathdoc},
     volume = {180},
     number = {2},
     year = {2007},
     doi = {10.4064/sm180-2-4},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/sm180-2-4/}
}