http://europepmc.org/abstract/MED/23632888
http://europepmc.org/abstract/MED/24218139
http://europepmc.org/abstract/MED/27486981
http://europepmc.org/abstract/MED/20601953
http://europepmc.org/abstract/MED/24030381
http://europepmc.org/abstract/MED/26648538
http://europepmc.org/abstract/MED/21909114