http://europepmc.org/abstract/MED/25846456
http://europepmc.org/abstract/MED/16211227
http://europepmc.org/abstract/MED/25846551
http://europepmc.org/abstract/MED/28481359
http://europepmc.org/abstract/MED/16459017
http://europepmc.org/abstract/MED/7852189