1. Berdyaev, Nicholas (1950) Dream and Reality. London, G. Bles.
2. Berkeley, George (1910) A New Theory of Vision and Other Writings. London, Dent
3. Engels, Frederick (1968) 'Ludwig Feuerbach and the End of Classical German Philosophy' in Marx and Engels, Selected Works in One Volume. London, Lawrence & Wishart.
4. Heidegger, Martin (1967) Being and Time. Oxford, Blackwell.