http://europepmc.org/abstract/MED/29844865
http://europepmc.org/abstract/MED/28481359
http://europepmc.org/abstract/MED/26071483
http://europepmc.org/abstract/MED/7972006
http://europepmc.org/abstract/MED/25617745
http://europepmc.org/abstract/MED/22895193
http://europepmc.org/abstract/MED/25344691
http://europepmc.org/abstract/MED/22810696