1. Tractica. Anzahl der Nutzer virtueller digitaler Assistenten weltweit in den Jahren von 2015 bis 2021 (in Millionen). Statista (2016)
2. Porter, J., Pino, N., Leger, H.: Amazon Echo vs Apple HomePod vs Google Home: the battle of the smart speakers (2019). https://www.techradar.com/news/amazon-echo-vs-homepod-vs-google-home-the-battle-of-the-smart-speakers. Accessed 29 Nov 2021
3. Gebhart, A., Price, M.: The best smart speakers for 2019 (2019). https://www.cnet.com/news/best-smart-speakers-for-2019-amazon-echo-dot-google-nest-mini-assistant-alexa/. Accessed 29 Nov 2021
4. Van Camp, J.: The 8 best smart speakers with Alexa and Google Assistant (2019). https://www.wired.com/story/best-smart-speakers/. Accessed 29 Nov 2021
5. Hassenzahl, M.: The hedonic/pragmatic model of user experience. Towards a UX manifesto (2007)