http://europepmc.org/abstract/MED/24793135
http://europepmc.org/abstract/MED/16518851
http://europepmc.org/abstract/MED/22142829
http://europepmc.org/abstract/MED/26822237
http://europepmc.org/abstract/MED/24436047
http://europepmc.org/abstract/MED/19681119
http://europepmc.org/abstract/MED/24332040