Gilad M. Lerman, Yanai, Avner , and Levy, Uriel . 2009. “Demonstration Of Nanofocusing By The Use Of Plasmonic Lens Illuminated With Radially Polarized Light”. Nano Letters, 9, 5, Pp. 2139-2143. https://pubs.acs.org/doi/abs/10.1021/nl900694r.