Department of Mathematical Sciences, University of Liverpool, Liverpool, L69 3BX, UK
Bibliografia
[1] V. I. Arnol'd, The geometry of spherical curves and the algebra of quaternions (in Russian), Uspekhi Mat. Nauk 50:1 (1995), 3-68; Engl. transl.: Russian Math. Surveys 50:1 (1995), 1-68.
[2] I. R. Porteous, Geometric Differentiation for the Intelligence of Curves and Surfaces, Cambridge Univ. Press, Cambridge, 1994.