http://europepmc.org/abstract/MED/28481359
http://europepmc.org/abstract/MED/22158988
http://europepmc.org/abstract/MED/27245685
http://europepmc.org/abstract/MED/27432539
http://europepmc.org/abstract/MED/24518503
http://europepmc.org/abstract/MED/21775669