http://europepmc.org/abstract/MED/25964599
http://europepmc.org/abstract/MED/24850867
http://europepmc.org/abstract/MED/22389253
http://europepmc.org/abstract/MED/22343920
http://europepmc.org/abstract/MED/24030381
http://europepmc.org/abstract/MED/27127180
http://europepmc.org/abstract/MED/21909114