http://europepmc.org/abstract/MED/8110876
http://europepmc.org/abstract/MED/25343957
http://europepmc.org/abstract/MED/27029036
http://europepmc.org/abstract/MED/2040694
http://europepmc.org/abstract/MED/24212482
http://europepmc.org/abstract/MED/17361096
http://europepmc.org/abstract/MED/7658697