Sykes, Bryan
The nature of the beast: the first scientific evidence on the survival of apemen into modern times
Hodder & Stoughton Ltd., 2014
 Buku Teks
Mason, Jennifer
Qualitative researching
Sage, 2009
 Buku Teks SO
Qualitative research
edited by Alan Bryman, Robert G. Burgess
SAGE Publication, 1999
 Buku Teks SO
McKibben, Bill
The end of nature
Random House, 1989
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Postlethwait, John H.
The nature of life
McGraw-Hill Publishing Company, 1989
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