@article{1183530226,
author = {Andrews, J. J. and Lomonaco, S. J.},
title = {The second homotopy group of spun 2-spheres in 4-space},
journal = {Bull. Amer. Math. Soc.},
volume = {75},
number = {5},
year = {1969},
pages = { 169-171},
language = {en},
url = {http://dml.mathdoc.fr/item/1183530226}
}
Andrews, J. J.; Lomonaco, S. J. The second homotopy group of spun 2-spheres in 4-space. Bull. Amer. Math. Soc., Tome 75 (1969) no. 5, pp. 169-171. http://gdmltest.u-ga.fr/item/1183530226/