The Lusternik-Schnirelman categories of a product space
Compositio Mathematica, Tome 22 (1970) no. 2, p. 175-180
@article{CM_1970__22_2_175_0,
     author = {Takens, Floris},
     title = {The Lusternik-Schnirelman categories of a product space},
     journal = {Compositio Mathematica},
     publisher = {Wolters-Noordhoff Publishing},
     volume = {22},
     number = {2},
     year = {1970},
     pages = {175-180},
     zbl = {0198.28302},
     mrnumber = {290365},
     language = {en},
     url = {http://www.numdam.org/item/CM_1970__22_2_175_0}
}
Takens, Floris. The Lusternik-Schnirelman categories of a product space. Compositio Mathematica, Tome 22 (1970) no. 2, pp. 175-180. http://www.numdam.org/item/CM_1970__22_2_175_0/

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