@article{CM_1970__22_2_175_0, author = {Takens, Floris}, title = {The {Lusternik-Schnirelman} categories of a product space}, journal = {Compositio Mathematica}, pages = {175--180}, publisher = {Wolters-Noordhoff Publishing}, volume = {22}, number = {2}, year = {1970}, mrnumber = {290365}, zbl = {0198.28302}, language = {en}, url = {http://archive.numdam.org/item/CM_1970__22_2_175_0/} }