1. Ashton, Thomas S. (1948), online edition The Industrial Revolution (1760–1830), Oxford University Press, ISBN 0195002520, retrieved 2009-07-26
2. Ayer, Alfred Jules. Logical Positivism. Glencoe, Ill: Free Press, 1959.
3. Betz, Frederick. 2011. Managing Science: Methodology and Organization of Research (New York: Springer)
4. Carlton, Grace (1965), Friedrich Engels: The Shadow Prophet. London: Pall Mall Press
5. Carver, Terrell. (1989). Friedrich Engels: His Life and Thought. London: Macmillan