1. R. Adams, Sobolev Spaces, Academic Press, 1975.
2. P. Ahern, M. Flores, and W. Rudin, An invariant volume-mean-value property, Jour. Functional Analysis 11(1993), 380–397.
3. L. Ahlfors, Complex Analysis, 3rd ed., McGraw-Hill, New York, 1979.
4. N. Aronszajn, Theory of reproducing kernels, Trans. Am. Math. Soc. 68(1950), 337–404.
5. T. N. Bailey, M. G. Eastwood, and C. R. Graham, Invariant theory for conformal and CR geometry, Annals of Math. 139(1994), 491–552.