http://europepmc.org/abstract/MED/26206799
http://europepmc.org/abstract/MED/22675565
http://europepmc.org/abstract/MED/28671688
http://europepmc.org/abstract/MED/12870051
http://europepmc.org/abstract/MED/8637233
http://europepmc.org/abstract/MED/8630377
http://europepmc.org/abstract/MED/7632931
http://europepmc.org/abstract/MED/28157215