A Derivation of K-Theory from M-Theory
  We show how some aspects of the K-theory classification of RR fluxes follow from a careful analysis of the phase of the M-theory action. This is a shortened and simplified companion paper to ``E8 Gauge Theory, and a Derivation of K-Theory from M-Theory.'' 
Diuliu-Emanuel Diaconescu, Gregory Moore, and Edward Witten