@article{MOMA_1990__110_3-4_178498,
     author = {Kurt Girstmair},
     title = {Drichlet {Convolution} of {Contangent} {Numbers} and {Relative} {Class} {Number} {Formulas.}},
     journal = {Monatshefte f\"ur Mathematik},
     pages = {231--256},
     publisher = {mathdoc},
     volume = {110},
     number = {3-4},
     year = {1990},
     zbl = {0717.11048},
     url = {http://geodesic.mathdoc.fr/item/MOMA_1990__110_3-4_178498/}
}