http://europepmc.org/abstract/MED/23996483
http://europepmc.org/abstract/MED/23648668
http://europepmc.org/abstract/MED/24531734
http://europepmc.org/abstract/MED/24127063
http://europepmc.org/abstract/MED/24608733
http://europepmc.org/abstract/MED/21880636
http://europepmc.org/abstract/MED/23443343