Reader's Digest Association & Shephard, S. (2004). The Amazing secrets of nature (1st English language ed.). Reader's Digest.
Chicago-viite (17. p.)Reader's Digest Association ja Sandy Shephard. The Amazing Secrets of Nature. 1st English language ed. New York: Reader's Digest, 2004.
MLA-viite (9. p.)Reader's Digest Association ja Sandy Shephard. The Amazing Secrets of Nature. 1st English language ed. Reader's Digest, 2004.
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