Schulz, U., P. Munzert, C. Präfke, F. Rickelt, and N. Kaiser. “Wide-Angle Broadband AR Coating by Combining Interference Layers With a Plasma-Etched Gradient Layer”. International Conference on Plasma Surface Engineering, vol. 2, no. 13, Mar. 2013, pp. 181-3, doi:10.3384/wcc2.181-183.