Phong, P.H., et al. “Voltammetric Behaviour of Two Stacking Layers of Copper-Bound 3-Mercaptopropionic Self-Assembled Monolayers on Gold Electrode and Application in Enhancement of Detection of Cu(II)”. Asian Journal of Chemistry, vol. 25, no. 3, Oct. 2012, pp. 1456-60, doi:10.14233/ajchem.2013.13077.