@article{MZ_1970__117_171425,
     author = {Claus Michael Ringel},
     title = {Diagonalisierungspaare. {I.}},
     journal = {Mathematische Zeitschrift},
     pages = {249--266},
     publisher = {mathdoc},
     volume = {117},
     year = {1970},
     zbl = {0206.30002},
     url = {http://geodesic.mathdoc.fr/item/MZ_1970__117_171425/}
}