http://europepmc.org/abstract/MED/8408453
http://europepmc.org/abstract/MED/26971368
http://europepmc.org/abstract/MED/29615459
http://europepmc.org/abstract/MED/28481359
http://europepmc.org/abstract/MED/8630516
http://europepmc.org/abstract/MED/9861322