http://europepmc.org/abstract/MED/14969745
http://europepmc.org/abstract/MED/8396224
http://europepmc.org/abstract/MED/1933879
http://europepmc.org/abstract/MED/8180965
http://europepmc.org/abstract/MED/9615731
http://europepmc.org/abstract/MED/21060032
http://europepmc.org/abstract/MED/22832583
http://europepmc.org/abstract/MED/8640736