Your conclusions should be based primarily on data described in your results section, although you may cite other literature to support and corroborate your conclusions and put them in a broader context. A good discussion section 'closes the circle' of the scientific method and suggests possible modifications of your orginial hypotheses, or further questions that have been raised. Be careful, however, to avoid making wild speculations and drawing in unnecessary information. All references mentioned in your paper should be cited, and only those references utilized in the text of your paper should be cited. Any statement of fact that is not obvious requires a literature citation in your paper.
Proper formats vary from journal to journal and professor to professor.
Books Wetzel, R.G. and G.E. Likens. 1991. Journal Articles Effler, S.W. and R.D. Hennigan. Wodka, S.H. 1970. Pesticides since Silent Spring . The Environmental Handbook.