@article{10_4153_CJM_1971_009_2,
     author = {Burde, Gerhard},
     title = {On {Branched} {Coverings} of {S3}},
     journal = {Canadian journal of mathematics},
     pages = {84--89},
     year = {1971},
     volume = {23},
     number = {1},
     doi = {10.4153/CJM-1971-009-2},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1971-009-2/}
}