http://europepmc.org/abstract/MED/25809997
http://europepmc.org/abstract/MED/27486981
http://europepmc.org/abstract/MED/16870548
http://europepmc.org/abstract/MED/16704439
http://europepmc.org/abstract/MED/20421268
http://europepmc.org/abstract/MED/24030381
http://europepmc.org/abstract/MED/21707751
http://europepmc.org/abstract/MED/26648538
http://europepmc.org/abstract/MED/18055864