1. A. D. Aleksandrov, Intrinsic Geometry of Convex Surfaces [in Russian], Gostekhizdat, Moscow-Leningrad (1948).
2. K. Borsuk, ?On homeomorphisms preserving lengths of arcs,? Glas. Mat. Ser. III,16, No. 2, 307?311 (1981).
3. I. Herburt and M. Moszy?ska, ?On intrinsic embeddings,? Glas. Mat. Ser. III,22, No. 2, 421?427 (1987).
4. M. Moszy?ska, ?On rigid subsets of some manifolds,? Colloq. Math.,57, No. 2, 247?254 (1989).
5. I. Herburt, ?On intrinsic isometries and rigid subsets of Euclidean spaces,? Demonstratio Math.,22, No. 4, 1205?1227 (1989).