1. J. Crespo, J. Serra, R.W. Schafer, in: J. Serra, P. Salembier (Eds.), Image segmentation using connected filters, Workshop on Mathematical Morphology, Barcelona, 1993, pp. 52–57.
2. J. Crespo, Morphological connected filters and intra-region smoothing for image segmentation, Ph.D. thesis, School of Electrical and Computer Engineering, Georgia Institute of Technology (December 1993).
3. Locality and adjacency stability constraints for morphological connected operators;Crespo;Journal of Mathematical Imaging and Vision,1997
4. From connected operators to levelings;Meyer,1998
5. The levelings;Meyer,1998