http://europepmc.org/abstract/MED/12736494
http://europepmc.org/abstract/MED/7522496
http://europepmc.org/abstract/MED/8617485
http://europepmc.org/abstract/MED/9293447
http://europepmc.org/abstract/MED/8644855
http://europepmc.org/abstract/MED/7530783