1. Benko, K., Cieślak, W., Góźdź, S., Mozgawa, W.: On isoptic curves. An. Ştiinţ. Univ. Al. I. Cuza 36, 47–54 (1990)
2. Cieślak, W., Miernowski, A., Mozgawa, W.: Isoptics of a strictly convex curve. In: Global Differential Geometry and Global Analysis. Proc. Conf. Berlin, Ger. Lect. Notes Math., vol. 1481(1991), pp. 28–35 (1990)
3. Cieślak, W., Miernowski, A., Mozgawa, W.: Isoptics of a closed strictly convex curve II. Rend. Sem. Mat. Univ. Padova 96, 37–49 (1996)
4. Cieślak, W., Miernowski, A., Mozgawa, W.: $$\varphi $$-optics and generalized Bianchi–Auerbach equation. J. Geom. Phys. 62, 2337–2345 (2012)
5. Csima, G., Szirmai, J.: Isoptic curves of conic sections in constant curvature geometries. Math. Commun. 19(2), 277–290 (2014)