3Sturgeon CM, Seth J. Why do immunoassays for tumor markers give differing results?--a view from the UK National External Quality Assessment Schemes. Eur J Clin Chem Biochem, 1996, 34:755-759.
4Sturgeon CM. Tumor markers in the laboratory: closing the guideline-practice gap. Clin Biochem, 2001,34:353-359.