http://europepmc.org/abstract/MED/9515788
http://europepmc.org/abstract/MED/11113864
http://europepmc.org/abstract/MED/1375111
http://europepmc.org/abstract/MED/7812011
http://europepmc.org/abstract/MED/9354678
http://europepmc.org/abstract/MED/16596195
http://europepmc.org/abstract/MED/29386642
http://europepmc.org/abstract/MED/9058723
http://europepmc.org/abstract/MED/9262496
http://europepmc.org/abstract/MED/21796119
http://europepmc.org/abstract/MED/16105905
http://europepmc.org/abstract/MED/9395180
http://europepmc.org/abstract/MED/8916968
http://europepmc.org/abstract/MED/7756655