Christoph Helmberg Svatopluk Poljak Franz Rendl Henry Wolkowicz Combining Semidefinite and Polyhedral Relaxations for Integer Programs. 124-134 1995 conf/ipco/1995 IPCO db/conf/ipco/ipco1995.html#HelmbergPRW95 http://dx.doi.org/10.1007/3-540-59408-6_46