@article{10_4153_CJM_2002_022_6,
     author = {Stanley, Donald},
     title = {On the {Lusternik-Schnirelmann} {Category} of {Maps}},
     journal = {Canadian journal of mathematics},
     pages = {608--633},
     year = {2002},
     volume = {54},
     number = {3},
     doi = {10.4153/CJM-2002-022-6},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-2002-022-6/}
}