http://europepmc.org/abstract/MED/25855536
http://europepmc.org/abstract/MED/28481359
http://europepmc.org/abstract/MED/9369932
http://europepmc.org/abstract/MED/22156295
http://europepmc.org/abstract/MED/26378065
http://europepmc.org/abstract/MED/7927902