Reuven Bar-Yehuda Irad Yavneh A Factor-Two Approximation Algorithm for Two-Dimensional Phase Unwrapping. 123-139 2006 10 J. Graph Algorithms Appl. 2 http://jgaa.info/accepted/2006/Bar-YehudaYavneh2006.10.2.pdf db/journals/jgaa/jgaa10.html#Bar-YehudaY06