http://europepmc.org/abstract/MED/10706082
http://europepmc.org/abstract/MED/19545284
http://europepmc.org/abstract/MED/17464320
http://europepmc.org/abstract/MED/11310834
http://europepmc.org/abstract/MED/10702393
http://europepmc.org/abstract/MED/10706887
http://europepmc.org/abstract/MED/18572809
http://europepmc.org/abstract/MED/11493472