http://europepmc.org/abstract/MED/24943872
http://europepmc.org/abstract/MED/1913619
http://europepmc.org/abstract/MED/22256804
http://europepmc.org/abstract/MED/25724524
http://europepmc.org/abstract/MED/2668964
http://europepmc.org/abstract/MED/22067401