http://europepmc.org/abstract/MED/9851250
http://europepmc.org/abstract/MED/29615459
http://europepmc.org/abstract/MED/28481359
http://europepmc.org/abstract/MED/24798740
http://europepmc.org/abstract/MED/2679847
http://europepmc.org/abstract/MED/24702198
http://europepmc.org/abstract/MED/19147753