http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3930839/
http://www.ncbi.nlm.nih.gov/m/pubmed/14722212/?i=3&from=/15144135/related
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3930839/
http://www.ncbi.nlm.nih.gov/m/pubmed/14722212/?i=3&from=/15144135/related