1. Böhme T., Elkmann N., Felsch. T., Sack M.,: Service Robots for Façade Ceaning. IECON’98, 24th Annual Conference of the IEEE Industrial Electronics Society, Aachen 1998, pp. 1204–1207
2. Elkmann, N., Felsch, T.: Climbing Robot for Operation at Vertical Facades. Proceedings of CLAWAR 1998, First International Symposium on Mobile, Climbing and Walking Robots, Brussels 26–28. October, 1998, pp. 373–377
3. Elkmann, N, Schmucker, U., Böhme, T., Sack, M.: Service Robots für Facade Cleaning. Advanced Robotics: Beyond 2000. The 29th International Symposium on Robotics, 27th of April–1st of May Birmingham, 1998, pp. 373–377
4. Elkmann N.: New concepts of service robots for motion at facades. Dissertation. TU Vienna, 1999
5. Elkmann N., Felsch. T., Sack M., Böhme T.: Modular climbing robot for outdoor operations. Proceedings of CLAWAR 1999, Second International Conference on Climbing and Walking Robots, Portsmouth 13–15. September, 1999, pp. 413–419