http://europepmc.org/abstract/MED/9460999
http://europepmc.org/abstract/MED/17982662
http://europepmc.org/abstract/MED/11353048
http://europepmc.org/abstract/MED/7614480
http://europepmc.org/abstract/MED/28481359
http://europepmc.org/abstract/MED/12637159
http://europepmc.org/abstract/MED/10674608
http://europepmc.org/abstract/MED/23525077
http://europepmc.org/abstract/MED/11141476
http://europepmc.org/abstract/MED/16416221
http://europepmc.org/abstract/MED/8194706