http://europepmc.org/abstract/MED/9354451
http://europepmc.org/abstract/MED/22493355
http://europepmc.org/abstract/MED/23444215
http://europepmc.org/abstract/MED/15195137
http://europepmc.org/abstract/MED/20544847
http://europepmc.org/abstract/MED/19158841
http://europepmc.org/abstract/MED/20460471
http://europepmc.org/abstract/MED/22515704
http://europepmc.org/abstract/MED/26061100
http://europepmc.org/abstract/MED/10338330
http://europepmc.org/abstract/MED/18505964
http://europepmc.org/abstract/MED/17260012
http://europepmc.org/abstract/MED/20406486