*{{Cite book| publisher = Rudolf Steiner Press| isbn = 978-0-85440-328-8| last = Adams| first = George| title = Physical and Ethereal Spaces| location = London| date = 1978|url=https://archive.org/stream/AdamsGeorgePhysicalAndEtherealSpaces/Adams%20George%20-%20Physical%20and%20ethereal%20spaces_djvu.txt}} | *{{Cite book| publisher = Rudolf Steiner Press| isbn = 978-0-85440-328-8| last = Adams| first = George| title = Physical and Ethereal Spaces| location = London| date = 1978|url=https://archive.org/stream/AdamsGeorgePhysicalAndEtherealSpaces/Adams%20George%20-%20Physical%20and%20ethereal%20spaces_djvu.txt}} |