1. M. Jaros and L. Riha, "Cyclesphi," 2016. https://code.it4i.cz/blender/cyclesphi.
2. B. O. Community, "Blender - a 3d modelling and rendering package," 2017. http://www.blender.org.
3. F. Steinmetz and G. Hofmann, The Cycles Encyclopedia. blender.org, 2014.
4. W. Jakob, "Mitsuba renderer," 2010. http://www.mitsuba-renderer.org.
5. M. Pharr, G. Humphreys, and T. Vergauwen, "Luxrender," 2007. http://www.luxrender.net.