http://europepmc.org/abstract/MED/17488404
http://europepmc.org/abstract/MED/7930674
http://europepmc.org/abstract/MED/9277151
http://europepmc.org/abstract/MED/8912828
http://europepmc.org/abstract/MED/7997263
http://europepmc.org/abstract/MED/7923098