http://europepmc.org/abstract/MED/24388756
http://europepmc.org/abstract/MED/28481359
http://europepmc.org/abstract/MED/9354678
http://europepmc.org/abstract/MED/8338955
http://europepmc.org/abstract/MED/17609875
http://europepmc.org/abstract/MED/17881637
http://europepmc.org/abstract/MED/21796119
http://europepmc.org/abstract/MED/12176791
http://europepmc.org/abstract/MED/10956404