http://europepmc.org/abstract/MED/8751963
http://europepmc.org/abstract/MED/10229204
http://europepmc.org/abstract/MED/22493355
http://europepmc.org/abstract/MED/8562340
http://europepmc.org/abstract/MED/20544847
http://europepmc.org/abstract/MED/20460471