@book{steiner-ga20-de,
  author = {Steiner, Rudolf},
  title = {Vom Menschenrätsel (1916)},
  series = {Rudolf Steiner Gesamtausgabe},
  number = {20},
  edition = {5},
  publisher = {Rudolf Steiner Verlag},
  address = {Basel},
  isbn = {978-3-7274-0200-5},
  language = {german},
}

@book{steiner-ga20-en-mp1990,
  author = {Steiner, Rudolf},
  title = {The Riddle of Man (1990)},
  translator = {William Lindeman},
  publisher = {Mercury Press},
  address = {Spring Valley, New York},
  year = {1990},
  pagetotal = {167},
  isbn = {0-929979-13-3},
  language = {english},
  note = {GA 20; edition code MP1990},
}

@online{anthroposophyai-ga20,
  author = {Steiner, Rudolf},
  title = {Vom Menschenrätsel (1916) (GA 20), as served by anthroposophy.ai},
  url = {https://anthroposophy.ai/contents/20/},
  urldate = {2026-10-21},
  organization = {anthroposophy.ai},
  note = {Rudolf Steiner, Vom Menschenrätsel (1916) (GA 20), as served by anthroposophy.ai, https://anthroposophy.ai/ga/20/, register entry https://anthroposophy.ai/contents/20/, status as of 2026-10-21: German served; English editions MP1990.},
}