http://europepmc.org/abstract/MED/23856246
http://europepmc.org/abstract/MED/27091358
http://europepmc.org/abstract/MED/26599269
http://europepmc.org/abstract/MED/9614374
http://europepmc.org/abstract/MED/27545006
http://europepmc.org/abstract/MED/22696596
http://europepmc.org/abstract/MED/21816872