http://europepmc.org/abstract/MED/25148578
http://europepmc.org/abstract/MED/15133491
http://europepmc.org/abstract/MED/19234609
http://europepmc.org/abstract/MED/24265153
http://europepmc.org/abstract/MED/22817889
http://europepmc.org/abstract/MED/23890154