@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/