http://europepmc.org/abstract/MED/11333292
http://europepmc.org/abstract/MED/8932338
http://europepmc.org/abstract/MED/23352210
http://europepmc.org/abstract/MED/25730902
http://europepmc.org/abstract/MED/10999741
http://europepmc.org/abstract/MED/15246568
http://europepmc.org/abstract/MED/26806567