http://europepmc.org/abstract/MED/28481359
http://europepmc.org/abstract/MED/7586214
http://europepmc.org/abstract/MED/24633157
http://europepmc.org/abstract/MED/26474454
http://europepmc.org/abstract/MED/9811333
http://europepmc.org/abstract/MED/9185695