http://europepmc.org/abstract/MED/25148578
http://europepmc.org/abstract/MED/7923152
http://europepmc.org/abstract/MED/24265153
http://europepmc.org/abstract/MED/28481359
http://europepmc.org/abstract/MED/20544847
http://europepmc.org/abstract/MED/24265154
http://europepmc.org/abstract/MED/8611425
http://europepmc.org/abstract/MED/24336498