http://europepmc.org/abstract/MED/26503331
http://europepmc.org/abstract/MED/28481359
http://europepmc.org/abstract/MED/9624535
http://europepmc.org/abstract/MED/20668451
http://europepmc.org/abstract/MED/8631583
http://europepmc.org/abstract/MED/7606711
http://europepmc.org/abstract/MED/22696596