http://europepmc.org/abstract/MED/21964605
http://europepmc.org/abstract/MED/18757741
http://europepmc.org/abstract/MED/22975805
http://europepmc.org/abstract/MED/19967722
http://europepmc.org/abstract/MED/28481359
http://europepmc.org/abstract/MED/29681454
http://europepmc.org/abstract/MED/27923066
http://europepmc.org/abstract/MED/22980975
http://europepmc.org/abstract/MED/22089114