1. American Association for Advancement of Science (1989). A project 1061 panel report: Biological and health science. Washington
2. Baghavan, R. S. (1987). An introduction to the philosophy of Marxism (Part One). Socialist Platform.
3. Barnett, L. (2005). The universe and Dr. Einstein (Rev. and (Illustrated). Dover Publications Inc.
4. Brenowski, J. (1977). A sense of the future: Essays in natural philosophy. MIT Press.
5. Choi, M. Y. (2010). Professor Choi Moo-young’s physics lecture (7th ed.). Chaekgalpi.