1. S.J. Ahn, W. Rauh, M. Recknagel, Geometric fitting of lines, plane, circle, sphere and ellipse, ABW-Workshop 6, Technische Akademie Esslingen, 25–26 January 1999.
2. S.J. Ahn, W. Rauh, H.-J. Warnecke, Best-fit of implicit surfaces and plane curves, in: T. Lyche, L.L. Schumaker (Eds.), Mathematical Methods for Curves and Surfaces: Oslo 2000, Vanderbilt University Press, Nashville, TN, 2001.
3. Least-squares orthogonal distances fitting of circle, sphere, ellipse, hyperbola, and parabola;Ahn;Pattern Recognition,2001
4. S.J. Ahn, E. Westkämper, W. Rauh, Orthogonal distance fitting of parametric curves and surfaces, in: J. Levesley, I. Anderson, J.C. Mason (Eds.), Algorithms for Approximation IV, University of Huddersfield, 2002, pp. 122–129.
5. Optimization algorithms for generalized distance regression in metrology;Bartholomew-Biggs,2000