http://europepmc.org/abstract/MED/24714776
http://europepmc.org/abstract/MED/23658559
http://europepmc.org/abstract/MED/24926260
http://europepmc.org/abstract/MED/23851445
http://europepmc.org/abstract/MED/18632627
http://europepmc.org/abstract/MED/15048078