http://europepmc.org/abstract/MED/26160192
http://europepmc.org/abstract/MED/12065772
http://europepmc.org/abstract/MED/28481359
http://europepmc.org/abstract/MED/29634977
http://europepmc.org/abstract/MED/21443421
http://europepmc.org/abstract/MED/18042066
http://europepmc.org/abstract/MED/8651354