http://europepmc.org/abstract/MED/18549475
http://europepmc.org/abstract/MED/7882351
http://europepmc.org/abstract/MED/9484839
http://europepmc.org/abstract/MED/18559592
http://europepmc.org/abstract/MED/23047306
http://europepmc.org/abstract/MED/29594878
http://europepmc.org/abstract/MED/8521414
http://europepmc.org/abstract/MED/9673367
http://europepmc.org/abstract/MED/24736079