@article{10_4064_aa106_3_5,
     author = {Jean-Marie De Koninck and Nicolas Doyon and Imre K\'atai},
     title = {On the counting function for the {Niven} numbers},
     journal = {Acta Arithmetica},
     pages = {265--275},
     publisher = {mathdoc},
     volume = {106},
     number = {3},
     year = {2003},
     doi = {10.4064/aa106-3-5},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/aa106-3-5/}
}