http://europepmc.org/abstract/MED/25846456
http://europepmc.org/abstract/MED/25846551
http://europepmc.org/abstract/MED/23791828
http://europepmc.org/abstract/MED/15099937
http://europepmc.org/abstract/MED/11595686
http://europepmc.org/abstract/MED/16459017
http://europepmc.org/abstract/MED/20826764
http://europepmc.org/abstract/MED/8319218