Searchable full texts can be useful for locating a particular phrase or passage: I've listed those that we have available, or seem to be available through open sources. Where multiple versions are available, I've chosen the one that seems best to me. Note that the translations available for non-English works are not the ones you are using in this course. The de Beauvoir text is available in French for anyone with sufficient facility in that language.
George Berkeley: Collected Works. Part of InteLex Past Masters.
Sigmund Freud: Beyond the Pleasure Principle. Translated by C.J.M. Hubback.
Immanuel Kant: Toward Perpetual Peace and Other Writings on Politics, Peace, and History. Translated by David L. Colclasure.
Thucydides: History of the Peloponnesian War. Translated by Charles Forster Smith. Part of Loeb Classical Library.