@misc{proofwiki:chord-theorem,
   author = "Proofwiki",
   title = "Intersecting Chord Theorem",
   year = "2014",
   note = "\url{https://proofwiki.org/wiki/Intersecting_Chord_Theorem} [Online; accessed = 10-October-2016]"
}

@inbook{knorr-1989,
   author = "Wilbur Richard Knorr",
   title = "Textual Studies in Ancient and Medieval Geometry",
   publisher = {Birkh\"{a}user},
   year = "1989",
   address = "Boston",
   edition = "first",
   pages = "34--36"
}

@inbook{birkhoff-beatley-1959,
   author = "Georg David Birkhoff and Ralph Beatley",
   title = "Basic Geometry",
   publisher = "AMS Chelsea Publishing",
   year = "1959",
   address = "Providence, Rhode Island",
   edition = "third",
   pages = "150",
}

@misc{harrison,
   author = "John Harrison",
   title = {Theorem on product of segments of chords (in {HOL} Light)},
   year = "2010",
   note = "\url{https://github.com/jrh13/hol-light/blob/master/100/chords.ml}"
}

@article{Triangle-AFP,
  author  = {Manuel Eberl},
  title   = {Basic Geometric Properties of Triangles},
  journal = {Archive of Formal Proofs},
  month   = dec,
  year    = 2015,
  note    = {\url{http://isa-afp.org/entries/Triangle.shtml},
            Formal proof development},
  ISSN    = {2150-914x},
}