1. [C] Calvo, O.,Deformations of Branched Lefschetz Pencils. Bull. Bras. Math. Soc.26:N. 1 (1995), 67?83.
2. [C-S] Calvo, O; Soares, M.,Chern Numbers of a Kupka component, Ann. Inst. Fourier44:N. 4 (1994), 1219?1236.
3. [C-L] Cerveau, D.; Lins, A., Codimension one Foliations in ??n, n ? 3, with Kupka components, Complex Analytic Methods in Dynamical Systems (C. Camacho, A. Lins, R. Mossou, P. Sad., eds.), Astérisque,222: (1994), 93?133.
4. [G-H] Griffiths Ph., Harris J.,Principles of Algebraic Geometry, Pure & Applied Math. Wiley Intersc. New York, (1978).
5. [GM-L] Gómez-Mont X.; Lins A.,Structural stability of foliations with a meromorphic first integral. Topology,30: (1990), 315?334