http://europepmc.org/abstract/MED/15693850
http://europepmc.org/abstract/MED/16318864
http://europepmc.org/abstract/MED/8044781
http://europepmc.org/abstract/MED/1644659
http://europepmc.org/abstract/MED/9655287
http://europepmc.org/abstract/MED/7768632
http://europepmc.org/abstract/MED/15523690
http://europepmc.org/abstract/MED/1923503