http://europepmc.org/abstract/MED/7960232
http://europepmc.org/abstract/MED/22271473
http://europepmc.org/abstract/MED/1581890
http://europepmc.org/abstract/MED/28481359
http://europepmc.org/abstract/MED/25308272
http://europepmc.org/abstract/MED/21266528