@techreport{rosu-chen-ball-2008-tr-a, author = {Grigore Ro\c{s}u and Feng Chen and Thomas Ball}, title = {Synthesizing Monitors for Safety Properties -- This Time With Calls and Returns --}, year = 2007, month = October, Number = {UIUCDCS-R-2007-2908}, institution = {University of Illinois at Urbana-Champaign, Department of Computer Science} }