@book{steiner-ga291-de,
  author = {Steiner, Rudolf},
  title = {Das Wesen der Farben},
  series = {Rudolf Steiner Gesamtausgabe},
  number = {291},
  edition = {4},
  publisher = {Rudolf Steiner Verlag},
  address = {Basel},
  year = {1991},
  pagetotal = {256},
  isbn = {978-3-7274-6510-9},
  language = {german},
}

@book{steiner-ga291-en-rspc1935,
  author = {Steiner, Rudolf},
  title = {Colour},
  translator = {Harry Collison},
  publisher = {Rudolf Steiner Publishing Co.},
  year = {1935},
  language = {english},
  note = {GA 291; edition code RSPC1935},
}

@online{anthroposophyai-ga291,
  author = {Steiner, Rudolf},
  title = {Das Wesen der Farben (GA 291), as served by anthroposophy.ai},
  url = {https://anthroposophy.ai/contents/291/},
  urldate = {2026-10-21},
  organization = {anthroposophy.ai},
  note = {Rudolf Steiner, Das Wesen der Farben (GA 291), as served by anthroposophy.ai, https://anthroposophy.ai/ga/291/, register entry https://anthroposophy.ai/contents/291/, status as of 2026-10-21: German served; English editions RSPC1935.},
}