http://europepmc.org/abstract/MED/28557976
http://europepmc.org/abstract/MED/21390130
http://europepmc.org/abstract/MED/15684603
http://europepmc.org/abstract/MED/21680795
http://europepmc.org/abstract/MED/8219205
http://europepmc.org/abstract/MED/22897847
http://europepmc.org/abstract/MED/25790293