http://europepmc.org/abstract/MED/24816253
http://europepmc.org/abstract/MED/22037554
http://europepmc.org/abstract/MED/28481359
http://europepmc.org/abstract/MED/22484628
http://europepmc.org/abstract/MED/22009941
http://europepmc.org/abstract/MED/26489445