• M. Golubitsky, I.N. Stewart and D.G. Schaeffer. Singularities and Groups in Bifurcation Theory: Vol. II. Applied Mathematical Sciences; Springer-Verlag. 69 (1988) [PDF 42.0M]
• M. Golubitsky and D.G. Schaeffer. Singularities and Groups in Bifurcation Theory: Vol. I. Applied Mathematical Sciences, Springer-Verlag. 51 (1985) [PDF 44.8M]