http://europepmc.org/abstract/MED/23204322
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http://europepmc.org/abstract/MED/29368261
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http://europepmc.org/abstract/MED/7515658
http://europepmc.org/abstract/MED/14502807
http://europepmc.org/abstract/MED/20544848
http://europepmc.org/abstract/MED/22287596