4Kawazu Y, Okimura M, lshii T, et al. Varietal and seasonal differences in oxalate content of spinach..Scientia Horticulturae.2003,97: 203 -210.
5Bakr A A, Gawish R A. Trials to reduce nitrate and oxalate content in some leafy vegetables. 2 Interactive effects of the manipulating of the soil nutrient supply, different blanching media and preservation methods followed by cooking process. J. Sci. Food Agric.,1997,73: 169-178.
6Elia A, Santamaria P, Serio F. Nitrogen nutrition, yield and quality of spinach. J. Sci. Food Agric.,1998,76:341-346.
7Zhang Y P, Lin X Y, Zhang Y S et al. Effects of nitrogen levels and nitrate/ammonium ratios on oxalate concentrations of different forms in edible parts of spinach. Journal of Plant Nutrition,2005,28 (11): 2011-2025.
8Bohn T, Davidsson L, Walczyk T, et al. Fractional magnesium absorption is significantly lower in human subjects from a meal served with an oxalate-rich vegetable, spinach, as compared with a meal served with kale, a vegetable with a low oxalate content. British J. Nutr.,2004,91:601-606.
9Lewandowski S, Rodgers A L. Idiopathic calcium oxalate urolithiasis: risk factors and conservative treatment. Clinica Chimica Acta, 2004,345:17-34.
10Weaver C M, Heaney R P. Calcium in Human Health. Totowa NJ: Humana Press Inc.,2006:2-6.
10Harris A H,Freel R W,Hateh M. Serum Oxalate in Human Beings and Rats as Determined with the Use of Ion Chromatography [J]. J. Lab. Clin. Med., 2004,144 (1):45-52.
