http://europepmc.org/abstract/MED/24997135
http://europepmc.org/abstract/MED/20309946
http://europepmc.org/abstract/MED/28481359
http://europepmc.org/abstract/MED/19681124
http://europepmc.org/abstract/MED/22169481
http://europepmc.org/abstract/MED/22696596