http://europepmc.org/abstract/MED/8679444
http://europepmc.org/abstract/MED/7559077
http://europepmc.org/abstract/MED/28481359
http://europepmc.org/abstract/MED/9122044
http://europepmc.org/abstract/MED/7700630
http://europepmc.org/abstract/MED/9171999
http://europepmc.org/abstract/MED/22722839