http://europepmc.org/abstract/MED/9330602
http://europepmc.org/abstract/MED/18602395
http://europepmc.org/abstract/MED/28465371
http://europepmc.org/abstract/MED/28481359
http://europepmc.org/abstract/MED/21901162
http://europepmc.org/abstract/MED/28978093
http://europepmc.org/abstract/MED/19679059
http://europepmc.org/abstract/MED/20951698