@article{MOMA_1961__65_177131,
     author = {Frank L\"obell},
     title = {Der {Hjelmslevsche} {Mittelliniensatz} und verwandte {S\"atze.}},
     journal = {Monatshefte f\"ur Mathematik},
     pages = {249--251},
     publisher = {mathdoc},
     volume = {65},
     year = {1961},
     zbl = {0095.34704},
     url = {http://geodesic.mathdoc.fr/item/MOMA_1961__65_177131/}
}