Piper, H. W. (1962). The active universe: Pantheism and the concept of imagination in the English romantic poets. University of London, Athlone Press.
Lua i Stíl Chicago (17ú heag.)Piper, Herbert Walter. The Active Universe: Pantheism and the Concept of Imagination in the English Romantic Poets. London: University of London, Athlone Press, 1962.
Lua MLA (9ú heag.)Piper, Herbert Walter. The Active Universe: Pantheism and the Concept of Imagination in the English Romantic Poets. University of London, Athlone Press, 1962.
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