Below is a list of frequently used online databases that provide primary resources for original research. As primary resources, they represent original content created by authors, artists, etc. 

ACS Primary Resources

Early English Books Online (Chadwyck-Healy)
Provides access to digital page images of virtually every work printed in England, Ireland, Scotland, Wales, and British North America and works in English printed elsewhere from 1473 to 1700. Includes books, pamphlets, manuscripts, and newspapers. For searchable text of selected titles see Early English Books Online -Text Creation Partnership.

Past Masters (InteLex)
Contains selected full text of scholarly editions of many philosophers, theologians and literary writers: Anselm, Aquinas, Aristotle, Augustine, Austen, Chesterton, Descartes, Dewey, Feuerbach, Fichte, Foucault, Francis of Assisi, Hegel, Hobbes, Hume, Kant, Kierkegaard, Leibniz, Locke, Luther, Machiavelli, Marx and Engels, Merleau-Ponty, Montesquieu, Newman, Nietzsche, Ockham, Pascal, Peirce, Plato, Poinsot, Royce, Santayana, Schopenhauer, Shelley, Spinoza, Synge, Wittgenstein and Wollestonecraft, as well as collections for British Philosophy 1600-1900, The Continental Rationalists, The Latin Background: 1100-1550, and The Romantic Age.

Contemporary Literary Criticism (Gale)
Covering authors currently active or active during the latter part of the 20th Century, this resource brings together critical essays, reviews and other critical responses representing a range of views on novelists, poets, playwrights, journalists, philosophers and other creative and nonfiction writers across all areas of the world.