http://europepmc.org/abstract/MED/9120722
http://europepmc.org/abstract/MED/8060323
http://europepmc.org/abstract/MED/27588476
http://europepmc.org/abstract/MED/28481359
http://europepmc.org/abstract/MED/10557071
http://europepmc.org/abstract/MED/8631583
http://europepmc.org/abstract/MED/9484839
http://europepmc.org/abstract/MED/7591275
http://europepmc.org/abstract/MED/27105513