http://europepmc.org/abstract/MED/8358709
http://europepmc.org/abstract/MED/19380030
http://europepmc.org/abstract/MED/20920256
http://europepmc.org/abstract/MED/11579461
http://europepmc.org/abstract/MED/20299091
http://europepmc.org/abstract/MED/19579075