9Marion C. Fetter, BS. Calibration of a strip test for urinary uro- bilinogen using a mercuric chloride asssay with crystalline reference standers[J]. American Journal of Medical Technology, 1981,47: 729 - 735.
10Jung K. Quality control material for aetiviity determinations of urinary enzymes[J]. Clin Bioehem, 1988,21:53 - 57.