@article{MM2_1990__67_1_155505,
     author = {U. Balakrishnan and J. Sengupta},
     title = {On the sum ... {D(n)} ... (n + {N).}},
     journal = {Manuscripta mathematica},
     pages = {367--378},
     publisher = {mathdoc},
     volume = {67},
     number = {1},
     year = {1990},
     zbl = {0721.11036},
     url = {http://geodesic.mathdoc.fr/item/MM2_1990__67_1_155505/}
}