@TechReport{Ring:1996b,
  author = 	 "Ring, Mark B.
  title = 	 "Finding Promising Exploration Regions by Weighting
		  Expected Navigation Costs",  
  institution =  "GMD --- German National Research Center for Information Technology",
  year = 	 1996,
  type = 	 "Arbeitspapiere der GMD 987",
  month = 	 "April",
}