Nightingale, Florence
Notes on nursing: What it is, and what it is not
Churchill Livingstone, 1980
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Brue, Greg
Six sigma
McGraw-Hill, 2006
 Buku Teks
Liu Pai-Yu
Six A.M
Peking Foreign Languages Press 1953
 Buku Teks SO
Six strategies
Jun shi ke xue chu ban she, , 2005.
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Horrie, Chris
What is Islam?
Virgin Books, 1991
 Buku Teks SO