Peter Nissen  <br />Topography of solitude. Places of silence in early Carthusian spirituality,  in: Hein Blommestijn, Charles Caspers, Rijcklof Hofman, Frits Mertens, Peter Nissen & Huub Welzen (eds.), Seeing the seeker: explorations in the discipline of spirituality. A Festschrift for Kees Waaijman on the occasion of his 65th birthday, Leuven, Paris & Dudley (MA), 2008, 201-213 (= Studies in spirituality. Supplements, 19)<br />[Nissen 2008]