@article{1183514166,
author = {Morse, Marston},
title = {L-S-homotopy classes on the topological image of a projective plane},
journal = {Bull. Amer. Math. Soc.},
volume = {55},
number = {12},
year = {1949},
pages = { 981-1003},
language = {en},
url = {http://dml.mathdoc.fr/item/1183514166}
}
Morse, Marston. L-S-homotopy classes on the topological image of a projective plane. Bull. Amer. Math. Soc., Tome 55 (1949) no. 12, pp. 981-1003. http://gdmltest.u-ga.fr/item/1183514166/