http://europepmc.org/abstract/MED/8555068
http://europepmc.org/abstract/MED/7632963
http://europepmc.org/abstract/MED/27776115
http://europepmc.org/abstract/MED/7742527
http://europepmc.org/abstract/MED/10090949
http://europepmc.org/abstract/MED/7795238
http://europepmc.org/abstract/MED/21960589