http://europepmc.org/abstract/MED/11329143
http://europepmc.org/abstract/MED/17692090
http://europepmc.org/abstract/MED/10506718
http://europepmc.org/abstract/MED/9550561
http://europepmc.org/abstract/MED/9703286
http://europepmc.org/abstract/MED/11371136
http://europepmc.org/abstract/MED/8630996
http://europepmc.org/abstract/MED/11079169