http://europepmc.org/abstract/MED/27149842
http://europepmc.org/abstract/MED/24755471
http://europepmc.org/abstract/MED/25496513
http://europepmc.org/abstract/MED/16959974
http://europepmc.org/abstract/MED/24951259
http://europepmc.org/abstract/MED/22180306