@book{akman-sv,
    Author = "Akman, Varol",
    Title = "Unobstructed Shortest Paths in Polyhedral Environments",
    Series = "Lecture Notes in Computer Science",
    Publisher = "Springer-Verlag",
    Number = "251",
    Year = "1987",
    mykey = "akman",
    Wrfnote = "WRF has"
}