Mukherjee,Jayanta, Das,P.P and Chatterji,B.N. (1990):
On connectivity issues of ESPTA,
Pattern Recognition Letters, 11(9), 643-648.  Abstract. 
In this paper we review the connectivity properties of our 3D thinning algorithm ESPTA (Extended Safe Point Thinning Algorithm) and its other variations. We present a modification of ESPTA, called MESPTA, which preserves connectivity of the image while maintaining its 3D shape.