@article{MOMA_1980__89_177973,
     author = {Hans G\"unther Kopetzky},
     title = {Rationale {Approximationen} am {Einheitskreis.}},
     journal = {Monatshefte f\"ur Mathematik},
     pages = {293--300},
     publisher = {mathdoc},
     volume = {89},
     year = {1980},
     zbl = {0426.10042},
     url = {http://geodesic.mathdoc.fr/item/MOMA_1980__89_177973/}
}