@techreport {TR-1981-004,
   type = {Technical Report},
   author = {Terry Beyer, Sandra Hedetniemi, Stephen Hedetniemi, Andrzej Prowskuroski},
   title = {Graph Traversal with Minimum Stack Depth},
   institution = {University of Oregon, Computer and Information Sciences Department},
   number = TR-1981-004,
   year = 1981,
   note = {Available at \url{https://www.cs.uoregon.edu/Reports/TR-1981-004.pdf}},
}