http://europepmc.org/abstract/MED/8261448
http://europepmc.org/abstract/MED/11159175
http://europepmc.org/abstract/MED/8437842
http://europepmc.org/abstract/MED/25759019
http://europepmc.org/abstract/MED/23774526
http://europepmc.org/abstract/MED/8483937
http://europepmc.org/abstract/MED/25759020
http://europepmc.org/abstract/MED/15656799
http://europepmc.org/abstract/MED/9622088