http://europepmc.org/abstract/MED/15693850
http://europepmc.org/abstract/MED/8280379
http://europepmc.org/abstract/MED/27107065
http://europepmc.org/abstract/MED/9655287
http://europepmc.org/abstract/MED/7768632
http://europepmc.org/abstract/MED/15523690
http://europepmc.org/abstract/MED/1923503