@article{FORUM_1997__9_2_141819,
     author = {Wolfgang K\"uhnel and Peter Breuer},
     title = {The tightness of tubes.},
     journal = {Forum mathematicum},
     pages = {707--720},
     publisher = {mathdoc},
     volume = {9},
     number = {2},
     year = {1997},
     zbl = {0885.53065},
     url = {http://geodesic.mathdoc.fr/item/FORUM_1997__9_2_141819/}
}