http://europepmc.org/abstract/MED/24675358
http://europepmc.org/abstract/MED/11881786
http://europepmc.org/abstract/MED/24909177
http://europepmc.org/abstract/MED/22705117
http://europepmc.org/abstract/MED/29874541
http://europepmc.org/abstract/MED/8912818