http://europepmc.org/abstract/MED/8603340
http://europepmc.org/abstract/MED/9935200
http://europepmc.org/abstract/MED/9665476
http://europepmc.org/abstract/MED/10942797
http://europepmc.org/abstract/MED/11943335
http://europepmc.org/abstract/MED/20737480