http://europepmc.org/abstract/MED/20959480
http://europepmc.org/abstract/MED/19863445
http://europepmc.org/abstract/MED/16140927
http://europepmc.org/abstract/MED/28481359
http://europepmc.org/abstract/MED/24747642
http://europepmc.org/abstract/MED/27468715
http://europepmc.org/abstract/MED/21733995