http://europepmc.org/abstract/MED/7551935
http://europepmc.org/abstract/MED/28481359
http://europepmc.org/abstract/MED/20668451
http://europepmc.org/abstract/MED/24594201
http://europepmc.org/abstract/MED/9808427
http://europepmc.org/abstract/MED/26273378
http://europepmc.org/abstract/MED/8395679
http://europepmc.org/abstract/MED/26729443