1. Barfield, Owen (1971). What Coleridge Thought, Wesleyan University Press.
2. Callaghan, Madeleine (2022). Eternity in British Romantic Poetry, Liverpool University Press.
3. Engell, James (1956a). The Collected Letters of Samuel Taylor Coleridge, Clarendon Press. 6 vols.
4. Engell, James (1956b). The Collected Letters of Samuel Taylor Coleridge, Clarendon Press. 6 vols.
5. Rooke, Barbara E. (1969). The Friend, Princeton University Press. The Collected Works of Samuel Taylor Coleridge 4.