@article{FORUM_1991__3_2_186389,
     author = {Rainer Schimming},
     title = {Harmonic {Differential} {Operators.}},
     journal = {Forum mathematicum},
     pages = {177--204},
     publisher = {mathdoc},
     volume = {3},
     number = {2},
     year = {1991},
     zbl = {0719.58040},
     url = {http://geodesic.mathdoc.fr/item/FORUM_1991__3_2_186389/}
}