Mirabi, A., et al. “Determination of Trace Amounts of Nickel in Food and Environmental Water Samples by Flame Atomic Absorption Spectrometry After Dispersive Liquid-Liquid Microextraction”. Asian Journal of Chemistry, vol. 24, no. 8, Apr. 2012, pp. 3425-9, https://asianpubs.org/index.php/ajchem/article/view/9388.