http://europepmc.org/abstract/MED/15921012
http://europepmc.org/abstract/MED/16107887
http://europepmc.org/abstract/MED/16086416
http://europepmc.org/abstract/MED/15852431
http://europepmc.org/abstract/MED/12763927
http://europepmc.org/abstract/MED/18755494