@Article{HH74,
    Author       = "Harary, F. and Hell, P.",
    Year         = "1974",
    Title        = "{Generalized Ramsey Theory for Graphs V: The Ramsey Number of a Digraph}",
    Journal      = "Bulletin of the London Mathematical Society",
    Volume       = "6",
    Pages        = "175-182",
    Comment      = "TPTPRef"
}