http://europepmc.org/abstract/MED/25809997
http://europepmc.org/abstract/MED/19075190
http://europepmc.org/abstract/MED/18925961
http://europepmc.org/abstract/MED/23319568
http://europepmc.org/abstract/MED/24030381
http://europepmc.org/abstract/MED/20644105
http://europepmc.org/abstract/MED/26648538