http://europepmc.org/abstract/MED/9466649
http://europepmc.org/abstract/MED/11801555
http://europepmc.org/abstract/MED/10492244
http://europepmc.org/abstract/MED/7957118
http://europepmc.org/abstract/MED/29941343
http://europepmc.org/abstract/MED/8731915
http://europepmc.org/abstract/MED/21822268
http://europepmc.org/abstract/MED/15308588