http://europepmc.org/abstract/MED/8631591
http://europepmc.org/abstract/MED/8261448
http://europepmc.org/abstract/MED/11981662
http://europepmc.org/abstract/MED/11159175
http://europepmc.org/abstract/MED/28481359
http://europepmc.org/abstract/MED/25759019
http://europepmc.org/abstract/MED/23774526
http://europepmc.org/abstract/MED/8483937
http://europepmc.org/abstract/MED/9349508