http://europepmc.org/abstract/MED/26617880
http://europepmc.org/abstract/MED/24030748
http://europepmc.org/abstract/MED/28419269
http://europepmc.org/abstract/MED/25427834
http://europepmc.org/abstract/MED/26919320
http://europepmc.org/abstract/MED/19554337
http://europepmc.org/abstract/MED/23840696