http://europepmc.org/abstract/MED/21798893
http://europepmc.org/abstract/MED/26934577
http://europepmc.org/abstract/MED/10694947
http://europepmc.org/abstract/MED/21798897
http://europepmc.org/abstract/MED/28481359
http://europepmc.org/abstract/MED/12118338
http://europepmc.org/abstract/MED/24436120
http://europepmc.org/abstract/MED/27050151