http://europepmc.org/abstract/MED/24986214
http://europepmc.org/abstract/MED/28481359
http://europepmc.org/abstract/MED/26891131
http://europepmc.org/abstract/MED/8198970
http://europepmc.org/abstract/MED/15492995
http://europepmc.org/abstract/MED/8644845
http://europepmc.org/abstract/MED/9445137