http://europepmc.org/abstract/MED/18419788
http://europepmc.org/abstract/MED/16140927
http://europepmc.org/abstract/MED/21084400
http://europepmc.org/abstract/MED/26317117
http://europepmc.org/abstract/MED/18647815
http://europepmc.org/abstract/MED/27468715
http://europepmc.org/abstract/MED/25490274
http://europepmc.org/abstract/MED/21733995