@techreport {TR-1986-006,
   type = {Technical Report},
   author = {Kent Stevens, Allen Brookes},
   title = {Probing Depth in Monocular Images },
   institution = {University of Oregon, Computer and Information Sciences Department},
   number = TR-1986-006,
   year = 1986,
   note = {Available at \url{https://www.cs.uoregon.edu/Reports/TR-1986-006.pdf}},
}