@article{GDZPPN002065630, title = {k-Invariants of knotted 2-spheres.}, journal = {Commentarii mathematici Helvetici}, volume = {60}, year = {1985}, pages = {54-84}, zbl = {0568.57017}, url = {http://dml.mathdoc.fr/item/GDZPPN002065630} }
Plotnick, S.P.; Suciu, A. I. k-Invariants of knotted 2-spheres.. Commentarii mathematici Helvetici, Tome 60 (1985) pp. 54-84. http://gdmltest.u-ga.fr/item/GDZPPN002065630/