http://europepmc.org/abstract/MED/18070147
http://europepmc.org/abstract/MED/29085338
http://europepmc.org/abstract/MED/20526288
http://europepmc.org/abstract/MED/23590130
http://europepmc.org/abstract/MED/25648502
http://europepmc.org/abstract/MED/23625203
http://europepmc.org/abstract/MED/19809427