1. Aghaei, S., Nematbakhsh, M.A., Farsani, H.K. (2012). Evolution of the World Wide Web:From Web 1.0 to Web 4.0. International Journal of Web & Semantic Technology (IJWesT), 3 (1), 1-10. doi: 10.5121/ijwest.2012.3101.
2. Allmendinger, G. and Lombreglia, R. (2005). Four Strategies for the Age of Smart Services, Harvard Business Review. Retrieved from https://hbr.org/2005/10/four-strategies-for-the-age-of-smart-services.
3. Arp, L. (2015, December 11). Do you know these popular online business models? Retrieved from http://sunriseprowebsites.com/know-popular-online-business-models.
4. Bley, S., Dr. Kilger, C., & Prof. Dr. Vogel, J. (2016). Industrie 4.0 — das unbekannte Wesen?. Ernst & Young GmbH. Retrieved from http://www.ey.com/Publication/vwLUAssets/EY-industrie-4-0-das-unbekannte-wesen/$FILE/EY-industrie-4-0-das-unbekannte-wesen.pdf.
5. BMBF - Federal Ministry of Education and Research. (2014). The new High-Tech Strategy Innovations for Germany. Retrieved from https://www.bmbf.de/pub/HTS_Broschuere_eng.pdf