Ward, Michael. " Mars." Planet Narnia: The Seven Heavens in the Imagination of C. S. Lewis. : Oxford University Press, 2008-03-01. Oxford Scholarship Online. 2008-01-01. Date Accessed 25 May. 2013 <http://www.oxfordscholarship.com/view/10.1093/acprof:oso/9780195313871.001.0001/acprof-9780195313871-chapter-4>.
Ward, M.(2008-03-01). Mars. In Planet Narnia: The Seven Heavens in the Imagination of C. S. Lewis. : Oxford University Press. Retrieved 25 May. 2013, from http://www.oxfordscholarship.com/view/10.1093/acprof:oso/9780195313871.001.0001/acprof-9780195313871-chapter-4.
Ward, Michael. " Mars." In Planet Narnia: The Seven Heavens in the Imagination of C. S. Lewis. : Oxford University Press, 2008-03-01. http://www.oxfordscholarship.com/view/10.1093/acprof:oso/9780195313871.001.0001/acprof-9780195313871-chapter-4.
Ward M. Mars. In: Ward M. Planet Narnia: The Seven Heavens in the Imagination of C. S. Lewis. Oxford University Press; 2008. http://www.oxfordscholarship.com/view/10.1093/acprof:oso/9780195313871.001.0001/acprof-9780195313871-chapter-4. Accessed May 25, 2013.