http://europepmc.org/abstract/MED/25964599
http://europepmc.org/abstract/MED/24850867
http://europepmc.org/abstract/MED/22343920
http://europepmc.org/abstract/MED/24608733
http://europepmc.org/abstract/MED/21909114
http://europepmc.org/abstract/MED/23443343