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http://europepmc.org/abstract/MED/18628094
http://europepmc.org/abstract/MED/23548132
http://europepmc.org/abstract/MED/21712828
http://europepmc.org/abstract/MED/23136868
http://europepmc.org/abstract/MED/20616366
http://europepmc.org/abstract/MED/21704278
http://europepmc.org/abstract/MED/18592002
http://europepmc.org/abstract/MED/24642870