N. T. H. Lien, V. X. Hoa, V. T. T. Duong, N. V. Tinh, and T. H. Nhung, “Synthesis and Optical Properties of Colloidal Gold Nanoparticles for Biomedical Applications”, Comm. Phys., vol. 21, no. 1, p. 63, Mar. 2011.