http://europepmc.org/abstract/MED/27148695
http://europepmc.org/abstract/MED/22610119
http://europepmc.org/abstract/MED/7604888
http://europepmc.org/abstract/MED/16941491
http://europepmc.org/abstract/MED/7872719
http://europepmc.org/abstract/MED/26000489
http://europepmc.org/abstract/MED/15541116