http://europepmc.org/abstract/MED/8562942
http://europepmc.org/abstract/MED/23856246
http://europepmc.org/abstract/MED/9060559
http://europepmc.org/abstract/MED/27776115
http://europepmc.org/abstract/MED/27884971
http://europepmc.org/abstract/MED/23334668
http://europepmc.org/abstract/MED/27872090
http://europepmc.org/abstract/MED/7845017
http://europepmc.org/abstract/MED/14639659
http://europepmc.org/abstract/MED/7723391
http://europepmc.org/abstract/MED/24619868
http://europepmc.org/abstract/MED/10071127