http://europepmc.org/abstract/MED/8562942
http://europepmc.org/abstract/MED/23334668
http://europepmc.org/abstract/MED/7723391
http://europepmc.org/abstract/MED/27776115
http://europepmc.org/abstract/MED/24619868
http://europepmc.org/abstract/MED/10071127