1. for a review on spin glasses see e.g. K. Binder and A.P. Young, Rev. Mod. Phys. 58, 801 (1986).
2. M. Alba, J. Hamman, M. Ocio, Ph. Refregier and H. Bouchiat, J. Appl. Phys..61, 3683 (1987).
3. P. Granberg, P. Svedlindh, P. Nordblad and L. Lundgren, in Proc. Heidelberg Colloquium on Glassy Dynamics, Heidelberg, West Germany, 1986, ed. J.L. van Hemmen and I. Morgenstern ( Springer-Verlag, Heidelberg, 1987 ).
4. L. Lundgren, P. Svedlindh and O. Beckman, Phys. Rev. B26, 3990 (1982).
5. L. Lundgren, P. Svedlindh, P. Nordblad and O. Beckman, Phys. Rev. Lett. B1, 911 (1983)