books.google.fr - ''Lusternik-Schnirelmann category is like a Picasso painting. Looking at category from different perspectives produces completely different impressions of category's beauty and applicability.'' --from the Introduction Lusternik-Schnirelmann category is a subject with ties to both algebraic topology and...http://books.google.fr/books/about/Lusternik_Schnirelmann_category.html?hl=fr&id=vMREfNN-L4gC&utm_source=gb-gplus-shareLusternik-Schnirelmann category
