http://europepmc.org/abstract/MED/24816253
http://europepmc.org/abstract/MED/15064998
http://europepmc.org/abstract/MED/9460999
http://europepmc.org/abstract/MED/24816255
http://europepmc.org/abstract/MED/7606196
http://europepmc.org/abstract/MED/11837710
http://europepmc.org/abstract/MED/25656989