will help to extend the applicability of the HA to describe, for example, atom-dimer collisions at low energies. Summarizing, we have demonstrated the usefulness of the KVP formulated in terms of integral relations. We have shown the general validity of the formulation with several applications to the A = 2 , 3 systems. In particular, we have in mind the possible use of this technique for describing scattering states using bound state methods in systems with A ≥ 4, as for example the GFMC method or the stochastic variational method. This work was partly supported by DGI of MEC (Spain), contract No. FIS2008-01301. One of us (C.R.R.) thanks support by a predoctoral I3P grant from CSIC and the European Social Fund. Acknowledgments [1] A. Nogga et al., Phys. Rev. C67 , 034004 (2003) [2] A. Nogga, H. Kamada, W. Gl¨ ockle, and B.R. Barrett, Phys. Rev. C65 , 054003 (2002) [3] M. Viviani, A. Kievsky, and S. Rosati, Phys. Rev. C71 , 024006 (2005) [4] W. Gl¨ ockle, H. WitaGLYPH<suppress>la, D. H¨ uber, H. Kamada, and J. Golak, Phys. Rep. 274 , 107 (1994) [5] A. Kievsky, M. Viviani and S. Rosati, Phys. Rev. C64 , 024002 (2001) [6] B.M. Fisher et al., Phys. Rev. C74 , 034001 (2006) [7] A. Deltuva and A.C. Fonseca, Phys. Rev. C75 , 014005 (2007) [8] A. Kievsky et al., Phys. Rev. C58 , 3085 (1998) [9] R. Lazauskas et al., Phys. Rev. C71 , 034004 (2005) [10] S.C. Pieper, K. Varga, and R.B. Wiringa, Phys. Rev. C66 , 044310 (2002) [11] P. Navr´ atil, V.G. Gueorguiev, J.P. Vary, W.E. Ormand, and A. Nogga, Phys. Rev. Lett. 99 , 042501 (2007) [12] K.M. Nollett, S.C. Pieper, R.B. Wiringa, J. Carlson, and G.M. Hale, Phys. Rev. Lett. 99 , 022502 (2007) [13] S. Quaglioni and P. Navr´ atil, Phys. Rev. C79 , 044606 (2009) [14] F.E. Harris, Phys. Rev. Lett., 19 , 173 (1967) 23