http://europepmc.org/abstract/MED/26934577
http://europepmc.org/abstract/MED/28481359
http://europepmc.org/abstract/MED/24292195
http://europepmc.org/abstract/MED/21984974
http://europepmc.org/abstract/MED/27693639
http://europepmc.org/abstract/MED/27050151