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Milnor and Stasheff, Characteristic classes.
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Hatcher, Vector bundles and K-theory
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Hutchings, Introduction to higher homotopy groups and obstruction theory
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Hutchings, Cup products and intersections
Useful Facts
- Any morphism between principal \(G{\hbox{-}}\)bundles is an isomorphism.
- A principal \(G{\hbox{-}}\)bundle is trivial iff it admits a section.