http://europepmc.org/abstract/MED/22178590
http://europepmc.org/abstract/MED/25478808
http://europepmc.org/abstract/MED/25695693
http://europepmc.org/abstract/MED/25759539
http://europepmc.org/abstract/MED/9592195
http://europepmc.org/abstract/MED/9658320
http://europepmc.org/abstract/MED/24797764
http://europepmc.org/abstract/MED/26892442
http://europepmc.org/abstract/MED/28481359
http://europepmc.org/abstract/MED/15513360
http://europepmc.org/abstract/MED/27900363
http://europepmc.org/abstract/MED/26315110
http://europepmc.org/abstract/MED/11117578
http://europepmc.org/abstract/MED/9033644
http://europepmc.org/abstract/MED/9207270