http://europepmc.org/abstract/MED/27284958
http://europepmc.org/abstract/MED/7640217
http://europepmc.org/abstract/MED/27535334
http://europepmc.org/abstract/MED/7796417
http://europepmc.org/abstract/MED/7591270
http://europepmc.org/abstract/MED/7547249