http://europepmc.org/abstract/MED/23632888
http://europepmc.org/abstract/MED/27777939
http://europepmc.org/abstract/MED/24045501
http://europepmc.org/abstract/MED/21828135
http://europepmc.org/abstract/MED/24127063
http://europepmc.org/abstract/MED/24695057
http://europepmc.org/abstract/MED/23443343