http://europepmc.org/abstract/MED/1324794
http://europepmc.org/abstract/MED/28619094
http://europepmc.org/abstract/MED/26599269
http://europepmc.org/abstract/MED/28481359
http://europepmc.org/abstract/MED/7615358
http://europepmc.org/abstract/MED/29681454
http://europepmc.org/abstract/MED/10850436
http://europepmc.org/abstract/MED/15161705
http://europepmc.org/abstract/MED/15564288
http://europepmc.org/abstract/MED/7767998
http://europepmc.org/abstract/MED/22696596