http://europepmc.org/abstract/MED/18464243
http://europepmc.org/abstract/MED/16909133
http://europepmc.org/abstract/MED/8393432
http://europepmc.org/abstract/MED/1314024
http://europepmc.org/abstract/MED/11745420
http://europepmc.org/abstract/MED/27213811
http://europepmc.org/abstract/MED/15838390