1. Selbsteinschätzung des Sprachniveaus - Universität Koblenz $$\cdot $$ Landau. https://www.uni-koblenz-landau.de/de/usz/tandem/sprachnivieau
2. All you need to know about conversational AI platforms - Botpress (2020). https://botpress.com/blog/all-you-need-to-know-about-conversational-ai-platforms
3. Developer Stack to Build Chatbots - Botpress (2020). https://botpress.com/
4. avato consulting AG (2021). https://www.avato-consulting.com/
5. Liibot Overview - iPortal (2021). https://iportal-innovators.avato.net/content/technical-documentation/avato-iportal/liibot-overview/