1. Amundsen, C. (1993). The evolution of theory in distance education. In D. Keegan (Ed.), Theoretical principles of distance education (pp. 61–79). London, England: Routledge.
2. Arger, G. (1989). Talking to New England. In T. D. Evans & D. E. Nation (Eds.), Critical reflections on distance education (pp. 73–94). Lewes, England: Falmer Press.
3. Berge, Z. (2013). Distance training and education in the corporate sector. In M. G. Moore (Ed.), Handbook of distance education (3rd ed., pp. 609–624). New York, NY: Routledge.
4. Bernath, U., & Vidal, M. (2007). “The theories and the theorists: Why theory is important for research”: With Børje Holmberg – Michael Graham Moore Otto Peters. Distances et savoirs, 5(3), 427–457. Retrieved from https://www.cairn.info/revue-distances-et-savoirs-2007-3-page-427.htm
5. Bollnow, O. F. (1967). Dilthey, Eine Einführung in seine Philosophie. Stuttgart, Germany: Klett.