Haeckel, E. H. P. A., & McCabe, J. (1900). The riddle of the universe at the close of the nineteenth century. Harper.
Chicago Style (17th ed.) CitationHaeckel, Ernst Heinrich Philipp August, and Joseph McCabe. The Riddle of the Universe at the Close of the Nineteenth Century. New York: Harper, 1900.
MLA (9th ed.) CitationHaeckel, Ernst Heinrich Philipp August, and Joseph McCabe. The Riddle of the Universe at the Close of the Nineteenth Century. Harper, 1900.
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