@article{IM_1987__89_143484,
     author = {S. Yamada},
     title = {The minimal number of {Seifert} circles equals the braid index of a link.},
     journal = {Inventiones mathematicae},
     pages = {347--356},
     publisher = {mathdoc},
     volume = {89},
     year = {1987},
     zbl = {0634.57004},
     url = {http://geodesic.mathdoc.fr/item/IM_1987__89_143484/}
}