@article{PMIHES_1964__19__69_0,
     author = {Hudson, John F. P. and Zeeman, Eric Christopher},
     title = {On combinatorial isotopy},
     journal = {Publications Math\'ematiques de l'IH\'ES},
     pages = {69--94},
     publisher = {Institut des Hautes \'Etudes Scientifiques},
     volume = {19},
     year = {1964},
     zbl = {0136.21201},
     mrnumber = {163318},
     language = {en},
     url = {http://archive.numdam.org/item/PMIHES_1964__19__69_0/}
}