1. J. Arazy, S. Fisher, and J. Peetre,Hankel operators on weighted Bergman spaces, Amer. J. Math. 110 (1988), 989?1054.
2. S. Axler,Bergman spaces and their operators, Surveys of Some Results in Operator Theory, vol. 1, (J.B. Conway and B.B. Morrel, editors), Pitman Res. Notes Math. Ser. vol. 171, 1988, pp. 1?50.
3. S. Axler, P. Bourdon, and W. Ramey,Harmonic Function Theory, Springer-Verlag, New York, 1992.
4. R.R. Coifman, R. Rochberg,Representation theorems for holomorphic and harmonic functions, Ast�risque 77 (1980), 11?65.
5. M. Jovovi?,Compact Hankel operators on harmonic Bergman spaces, Integral Equations and Operator Theory 22 (1995), 295?304.