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@article{MM2_1983__42_154921, author = {Luis Montejano}, title = {A {Quick} proof of {Singhof's} cat {(M} x {S1)} = cat {(M)} + 1 theorem.}, journal = {Manuscripta mathematica}, pages = {49--52}, publisher = {mathdoc}, volume = {42}, year = {1983}, zbl = {0639.55001}, url = {http://geodesic.mathdoc.fr/item/MM2_1983__42_154921/} }
Luis Montejano. A Quick proof of Singhof's cat (M x S1) = cat (M) + 1 theorem.. Manuscripta mathematica, Tome 42 (1983), pp. 49-52. http://geodesic.mathdoc.fr/item/MM2_1983__42_154921/