Krutch, J. W., & Landacre, P. (2009). The great chain of life (1st University of Iowa Press ed.). University of Iowa Press.
Lua i Stíl Chicago (17ú heag.)Krutch, Joseph Wood, agus Paul Landacre. The Great Chain of Life. 1st University of Iowa Press ed. Iowa City: University of Iowa Press, 2009.
Lua MLA (9ú heag.)Krutch, Joseph Wood, agus Paul Landacre. The Great Chain of Life. 1st University of Iowa Press ed. University of Iowa Press, 2009.
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