@article{CMH_1975__50_139629,
     author = {Andrew Du Plessis},
     title = {Maps {Without} {Certain} {Singularities.}},
     journal = {Commentarii mathematici Helvetici},
     pages = {363--382},
     publisher = {mathdoc},
     volume = {50},
     year = {1975},
     zbl = {0313.58010},
     url = {http://geodesic.mathdoc.fr/item/CMH_1975__50_139629/}
}