http://europepmc.org/abstract/MED/1638540
http://europepmc.org/abstract/MED/14712292
http://europepmc.org/abstract/MED/23091298
http://europepmc.org/abstract/MED/23143597
http://europepmc.org/abstract/MED/8219205
http://europepmc.org/abstract/MED/1736012
http://europepmc.org/abstract/MED/7596184
http://europepmc.org/abstract/MED/12890146
http://europepmc.org/abstract/MED/7707106