Armstrong, R.J., Wayne Hellman, J. A. & Short, W. J., Francis of Assisi: Early Documents (New York, New City Press, 1999) - A three volume series: Vol. I, The Saint: Vol. II, The Founder: Vol. III, The Prophet;
Boff, Leonardo, Cry of the Earth: Cry of the Poor (Maryknoll, Orbis Books, 1997);
Delio, Ilia, A Franciscan View of Creation: Learning to Live in a Sacramental World (St. Bonaventure, NY, The Franciscan Institute, 2003);
Delio, Ilia, Douglass Warner, Keith, & Wood, Pamela, Care for Creation: A Franciscan Spirituality of the Earth (Cincinnati, St. Anthony Messenger Press, 2008);
Guinan, Michael D., Where In The World Are We? Old Testament Views of Creation, available in 6 audio cassettes or 10 CD's (Ohio, St. Pauls, 2005)
Guinan, Michael D., The Franciscan Vision and the Gospel of John: The San Damiano Cross, Francis and John, Creation and John (St. Bonaventure, NY, The Franciscan Institute, 2006);
Nothwehr, Dawn M. (ed), Franciscan Theology of the Environment: An Introductory Reader (Quincy, Franciscan Press, 2002);
Sorrell, Roger D., St. Francis of Assisi and Nature (New York, Oxford University Press, 1988)