Rassias (2001). Rassias, Themistocles M. (2001), "Isometric mappings and the problem of A. D. Aleksandrov for conservative distances", in Florian, H.; Ortner, N.; Schnitzer, F. J.; Tutschke, W. (eds.), Functional-Analytic and Complex Methods, their Interactions, and Applications to Partial Differential Equations: Proceedings of the International Workshop held at Graz University Of Technology, Graz, February 12–16, 2001, River Edge, New Jersey: World Scientific Publishing Co., Inc., pp. 118–125, doi:10.1142/4822, ISBN978-981-02-4764-5, MR1893253
Rassias (2001). Rassias, Themistocles M. (2001), "Isometric mappings and the problem of A. D. Aleksandrov for conservative distances", in Florian, H.; Ortner, N.; Schnitzer, F. J.; Tutschke, W. (eds.), Functional-Analytic and Complex Methods, their Interactions, and Applications to Partial Differential Equations: Proceedings of the International Workshop held at Graz University Of Technology, Graz, February 12–16, 2001, River Edge, New Jersey: World Scientific Publishing Co., Inc., pp. 118–125, doi:10.1142/4822, ISBN978-981-02-4764-5, MR1893253