@TechReport{nus-discs-trj3/92,
  author = 	 "C L TAN, S K K LOH",
  title = 	 "Efficient edge detection using hierarchical
                  structures",
  institution =  "National University of Singapore, Department of
                  Information Systems and Computer Science",
  year = 	 1992,
  number =	 "Technical Report TRJ3/92"
}