http://europepmc.org/abstract/MED/8988029
http://europepmc.org/abstract/MED/18549475
http://europepmc.org/abstract/MED/7882351
http://europepmc.org/abstract/MED/9120722
http://europepmc.org/abstract/MED/9484839
http://europepmc.org/abstract/MED/8521414
http://europepmc.org/abstract/MED/9673367