Douglas, P. H. (1933). Collapse or cycle? American library association.
Chicago Style (17th ed.) CitationDouglas, Paul Howard. Collapse or Cycle? Chicago: American library association, 1933.
MLA (8th ed.) CitationDouglas, Paul Howard. Collapse or Cycle? American library association, 1933.
Advarsel: Disse citationer er muligvist ikke 100% nøjagtige.