K-theory

Topological

Atiyah, K-theory

Hatcher, Vector bundles and K-theory

Karoubi, K-theory: an introduction

Park, Complex topological K-theory

Rordam et al, An introduction to K-theory for C^*-algebras

Algebraic

Weibel, The K-book: an introduction to algebraic K-theory

Magum, An algebraic introduction to K-theory

Dundas et al, The local structure of algebraic K-theory