http://europepmc.org/abstract/MED/19372580
http://europepmc.org/abstract/MED/22722201
http://europepmc.org/abstract/MED/23601657
http://europepmc.org/abstract/MED/27406316
http://europepmc.org/abstract/MED/28027327
http://europepmc.org/abstract/MED/25757876
http://europepmc.org/abstract/MED/22722202