@article{SM_2020_211_3_a1,
     author = {O. E. Galkin and S. Yu. Galkina},
     title = {Global extrema of the {Delange} function, bounds for digital sums and concave functions},
     journal = {Sbornik. Mathematics},
     pages = {336--372},
     publisher = {mathdoc},
     volume = {211},
     number = {3},
     year = {2020},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_2020_211_3_a1/}
}