1. Bengtsson, L., 1995. Snö och Is i Vattnets Kretslopp. In: Isfeldt, I. (ed.), NFR Årsbok 1995, Det Evigt Vandrande Vattnet, Stockholm, pp. 33–42.
2. Bengtsson, M., Lundin, M., Molander, S., 1997. Life cycle assessment of wastewater systems — case studies of conventional treatment, urine sorting and liquid composting in three Swedish municipalities. Chalmers University of Technology, Technical environmental planning, Report 1997:9, Göteborg, Sweden, pp. 99.
3. Characterization of the municipal wastewaterpart human urine and a preliminary comparison with liquid cattle excretion;Fittschen;Wat. Sci. Tech.,1998
4. Urease, the primary cause of infection-induced urinary stones;Griffith;Invest. Urol.,1976