http://europepmc.org/abstract/MED/27486981
http://europepmc.org/abstract/MED/18925961
http://europepmc.org/abstract/MED/14644997
http://europepmc.org/abstract/MED/24030381
http://europepmc.org/abstract/MED/26648538
http://europepmc.org/abstract/MED/25407606
http://europepmc.org/abstract/MED/15725481