@article{10_4064_sm_23_3_247_283,
     author = {E. Stein and A. Zygmund},
     title = {On the differentiability of functions},
     journal = {Studia Mathematica},
     pages = {247--283},
     year = {1963},
     volume = {23},
     number = {3},
     doi = {10.4064/sm-23-3-247-283},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/sm-23-3-247-283/}
}