@article{10_4064_ap_13_2_133_138,
     author = {B. Choczewski},
     title = {On differentiable solutions of a functional equation},
     journal = {Annales Polonici Mathematici},
     pages = {133--138},
     publisher = {mathdoc},
     volume = {13},
     number = {2},
     year = {1963},
     doi = {10.4064/ap-13-2-133-138},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/ap-13-2-133-138/}
}