http://europepmc.org/abstract/MED/24986214
http://europepmc.org/abstract/MED/24908143
http://europepmc.org/abstract/MED/28481359
http://europepmc.org/abstract/MED/26891131
http://europepmc.org/abstract/MED/9445137
http://europepmc.org/abstract/MED/8781571