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3. Bangert, V.: Hypersufaces without self-intersections in the torus, Twist mappings and their applications, 55–71, IMA Vol. Math. Appl., 44, Springer, New York, (1992)
4. Bangert, V.: On 2-tori having a pole, (preprint) (2009)
5. Bangert, V., Gutkin, E.: Secure two-dimensional tori are flat, (preprint) arXiv:0806.3572 (2008)