http://europepmc.org/abstract/MED/10209495
http://europepmc.org/abstract/MED/19036597
http://europepmc.org/abstract/MED/8040301
http://europepmc.org/abstract/MED/8617485
http://europepmc.org/abstract/MED/20962673
http://europepmc.org/abstract/MED/17970070
http://europepmc.org/abstract/MED/12907633
http://europepmc.org/abstract/MED/8076344