http://europepmc.org/abstract/MED/21390126
http://europepmc.org/abstract/MED/26608593
http://europepmc.org/abstract/MED/28302137
http://europepmc.org/abstract/MED/24388756
http://europepmc.org/abstract/MED/28481359
http://europepmc.org/abstract/MED/21796119
http://europepmc.org/abstract/MED/26647218