@article{MAN_1991__291_1_164887, author = {Kouki Taniyama}, title = {On unknotting operations of two-brigde knots.}, journal = {Mathematische Annalen}, pages = {579--590}, year = {1991}, volume = {291}, number = {1}, zbl = {0726.57009}, url = {http://geodesic.mathdoc.fr/item/MAN_1991__291_1_164887/} }