http://europepmc.org/abstract/MED/1349102
http://europepmc.org/abstract/MED/11023067
http://europepmc.org/abstract/MED/7841033
http://europepmc.org/abstract/MED/17582213
http://europepmc.org/abstract/MED/8393371
http://europepmc.org/abstract/MED/9155557
http://europepmc.org/abstract/MED/17521451
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