Browne, C., A. Di Battista, T. Geiger, and T. Gutknecht. 2014. “The Executive Opinion Survey: The Voice of the Business Community”. The Global Competitiveness Report 2014-2015. Geneva: World Economic Forum;
http://www.weforum.org/reports/global-competitiveness-report-2014-2015

Jacomy, M., S. Heymann, T. Venturini, and M. Bastian. 2012. «ForceAtlas2, A Continuous Graph Layout Algorithm for Handy Network Visualization»; http://www.medialab.sciences-po.fr/publications/Jacomy_Heymann_Venturini- Force_Atlas2.pdf.