http://europepmc.org/abstract/MED/24755523
http://europepmc.org/abstract/MED/19498322
http://europepmc.org/abstract/MED/27296931
http://europepmc.org/abstract/MED/17854394
http://europepmc.org/abstract/MED/27468715
http://europepmc.org/abstract/MED/27389594