http://europepmc.org/abstract/MED/8242616
http://europepmc.org/abstract/MED/8703846
http://europepmc.org/abstract/MED/11587234
http://europepmc.org/abstract/MED/8950979
http://europepmc.org/abstract/MED/10719372
http://europepmc.org/abstract/MED/22307741
http://europepmc.org/abstract/MED/10886213