@article{MOMA_1969__73_177481,
     author = {Richard Warlimont},
     title = {On {Squarefree} {Numbers} in {Arithmetic} {Progressions.}},
     journal = {Monatshefte f\"ur Mathematik},
     pages = {433--448},
     publisher = {mathdoc},
     volume = {73},
     year = {1969},
     zbl = {0213.33002},
     url = {http://geodesic.mathdoc.fr/item/MOMA_1969__73_177481/}
}