@article{MS2_1979__44_166645,
     author = {Bruce R. Ebanks},
     title = {On some functional equations of {Jessen,} {Karpf,} and {Thorup.}},
     journal = {Mathematica Scandinavica},
     pages = {231--234},
     publisher = {mathdoc},
     volume = {44},
     year = {1979},
     zbl = {0451.39007},
     url = {http://geodesic.mathdoc.fr/item/MS2_1979__44_166645/}
}