http://europepmc.org/abstract/MED/25850943
http://europepmc.org/abstract/MED/26527317
http://europepmc.org/abstract/MED/19372580
http://europepmc.org/abstract/MED/27406316
http://europepmc.org/abstract/MED/28027327
http://europepmc.org/abstract/MED/22722202
http://europepmc.org/abstract/MED/21512767