http://europepmc.org/abstract/MED/9816033
http://europepmc.org/abstract/MED/28481359
http://europepmc.org/abstract/MED/7834619
http://europepmc.org/abstract/MED/9355981
http://europepmc.org/abstract/MED/24956168
http://europepmc.org/abstract/MED/19375815
http://europepmc.org/abstract/MED/7478613