http://europepmc.org/abstract/MED/1996309
http://europepmc.org/abstract/MED/26503331
http://europepmc.org/abstract/MED/23515407
http://europepmc.org/abstract/MED/29681454
http://europepmc.org/abstract/MED/25376516
http://europepmc.org/abstract/MED/23136191