http://europepmc.org/abstract/MED/28481359
http://europepmc.org/abstract/MED/22844452
http://europepmc.org/abstract/MED/15450401
http://europepmc.org/abstract/MED/28270234
http://europepmc.org/abstract/MED/15929038
http://europepmc.org/abstract/MED/24880341
http://europepmc.org/abstract/MED/8548759