http://europepmc.org/abstract/MED/26650777
http://europepmc.org/abstract/MED/24755471
http://europepmc.org/abstract/MED/28481359
http://europepmc.org/abstract/MED/28978093
http://europepmc.org/abstract/MED/22810696
http://europepmc.org/abstract/MED/27756406