@inproceedings{bridges2021:285,
  author      = {Kekkonen, Hanne},
  title       = {Do the Angles of a Triangle Add up to 180°? - Introducing Non-Euclidean Geometry},
  pages       = {285--288},
  booktitle   = {Proceedings of Bridges 2021: Mathematics, Art, Music, Architecture, Culture},
  year        = {2021},
  editor      = {Swart, David and Farris, Frank and Torrence, Eve},
  isbn        = {978-1-938664-39-7},
  issn        = {1099-6702},
  publisher   = {Tessellations Publishing},
  address     = {Phoenix, Arizona},

  url         = {http://archive.bridgesmathart.org/2021/bridges2021-285.html}
}