http://europepmc.org/abstract/MED/22323480
http://europepmc.org/abstract/MED/27486981
http://europepmc.org/abstract/MED/25964599
http://europepmc.org/abstract/MED/24695057
http://europepmc.org/abstract/MED/26648538
http://europepmc.org/abstract/MED/21909114
http://europepmc.org/abstract/MED/23774674