A couple of references that spring to mind are Richard Hycner 'Between Person and Person', The Gestalt Journal Press, 1991 particularly chapter 6, The Spiritual Dimension in Psychotherapy; James Walker, 'Body and Soul; Gestalt therapy and religious experience, I don't have the details of the publisher; Wilson Van Dusen, 'The Natural Depth in Man', Swedenborg Foundation, New York, 1981 (previously Harper and Row publication 1975); A number of chapters in 'gestalt is' by John O Stevens, Real People Press, 1975, including Wilson Van Dusen 'Invoking the Actual' & ' Wu Wei, No Mind and the Fertile Void' and Stella Resnick, 'Gestalt Therapy as a Meditative Practice; and some of the writings of Claudio Naranjo, including his recent book 'Gestalt Therapy; The attitude and practice of an atheoretical experientialism'Gateways, Nevada, 1993.