http://europepmc.org/abstract/MED/24140581
http://europepmc.org/abstract/MED/26191234
http://europepmc.org/abstract/MED/28481359
http://europepmc.org/abstract/MED/28218421
http://europepmc.org/abstract/MED/24695838
http://europepmc.org/abstract/MED/23917401