Ravindra K. Ahuja Dorit S. Hochbaum James B. Orlin Solving the Convex Cost Integer Dual Network Flow Problem. 31-44 1999 conf/ipco/1999 IPCO http://link.springer.de/link/service/series/0558/bibs/1610/16100031.htm db/conf/ipco/ipco1999.html#AhujaHO99