http://europepmc.org/abstract/MED/19498322
http://europepmc.org/abstract/MED/28102204
http://europepmc.org/abstract/MED/26397949
http://europepmc.org/abstract/MED/23913004
http://europepmc.org/abstract/MED/26815163
http://europepmc.org/abstract/MED/27468715
http://europepmc.org/abstract/MED/23913001