http://europepmc.org/abstract/MED/22879364
http://europepmc.org/abstract/MED/20668451
http://europepmc.org/abstract/MED/19372580
http://europepmc.org/abstract/MED/19593635
http://europepmc.org/abstract/MED/24318467
http://europepmc.org/abstract/MED/28027327