http://europepmc.org/abstract/MED/22323480
http://europepmc.org/abstract/MED/26812887
http://europepmc.org/abstract/MED/27288520
http://europepmc.org/abstract/MED/27276561
http://europepmc.org/abstract/MED/26438511
http://europepmc.org/abstract/MED/27881874
http://europepmc.org/abstract/MED/23029227