@article{MM2_1974__13_154277,
     author = {W. Wilson Stothers},
     title = {Impossible {Specifications} for the {Modular} {Group.}},
     journal = {Manuscripta mathematica},
     pages = {415--428},
     publisher = {mathdoc},
     volume = {13},
     year = {1974},
     zbl = {0317.10038},
     url = {http://geodesic.mathdoc.fr/item/MM2_1974__13_154277/}
}