@phdthesis {PHD-200508-Sahr,
   type = {Dissertation Defense},
   author = {Kevin Sahr},
   title = {Discrete Global Systems: A New Class of Geospatial Data Structures},
   school = {College of Arts and Sciences, University of Oregon},
   month = 8,
   year = 2005,
   note = {Available at \url{https://www.cs.uoregon.edu/Reports/PHD-200508-Sahr.pdf}},
}