http://europepmc.org/abstract/MED/24792622
http://europepmc.org/abstract/MED/28481359
http://europepmc.org/abstract/MED/23770606
http://europepmc.org/abstract/MED/22057234
http://europepmc.org/abstract/MED/22057236
http://europepmc.org/abstract/MED/21598255