1. Gao Hongweii, 1993, Determination of ammonia-nitrogen in water by primary-secondary wavelengths spectrophotometry: Huanjing Kexue (Environmental Science), v. 14, p. 82–84 (in Chinese).
2. Gao Hongwen, 1994, Determination of iron with chrome azurol S by β-correction spectrophotometry: J. Hyg. Res., v. 23, p. 147–149 (in Chinese).
3. Gao Hongwen and P. F. Zhang, 1994, β-correction spectrophotometric determination of beryllium in wastewater with titan yellow: Anal. Proc., v. 31, p. 85–87.
4. Li, C. H. and Y. S. Chen, 1993, A demonstration for the principle of the mole ratio method: Fenxi Shiyanshi (Analytical Laboratory), v. 12, p. 31–33.
5. Valencia M. Carmen, Said Boudra and M. Bosque-Sendra, 1993, Determination of trace amounts of beryllium in water by solid-phase spectrophotometry: Analyst, v. 118, p. 1333–1336.