Russell, Robert John: "Ian Barbour's Methodological Breakthrough: Creating the 'Bridge' between Science and Theology". pp.45–59. In: Russell, R. J. (Ed.): Fifty Years in Science and Religion - Ian G. Barbour and his Legacy. Ashgate, Burlington 2004. Esp. p.45
Gregersen, Niels Henrik[da]: Critical Realism and Other Realisms. pp.77–95. In: Russell, R. J. (Ed.): Fifty Years in Science and Religion - Ian G. Barbour and his Legacy. Ashgate, Burlington 2004. Esp. p.77, 85-88.