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http://europepmc.org/abstract/MED/12168936
http://europepmc.org/abstract/MED/15012776
http://europepmc.org/abstract/MED/25724664
http://europepmc.org/abstract/MED/11149028
http://europepmc.org/abstract/MED/8760583
http://europepmc.org/abstract/MED/10928081
http://europepmc.org/abstract/MED/9989830