@article{10_4064_sm170_3_3,
     author = {J. Marshall Ash and Hajrudin Fejzi\'c},
     title = {Approximate and $L^{p}$ {Peano} derivatives
 of nonintegral order},
     journal = {Studia Mathematica},
     pages = {241--258},
     year = {2005},
     volume = {170},
     number = {3},
     doi = {10.4064/sm170-3-3},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/sm170-3-3/}
}