A real space renormalization is applied to the Ising model for d 3, allowing for the generation of vacancies. A fixed point structure is obtained that reflects the cross-over to classical behaviour as known from e-expansion. The exponents found are an improvement over those obtained by the same method applied to the Ising model without vacancies.
Rijpkema, J. J. M., & Knops, H. J. F. (1981). Cross-over to classical behaviour for an Ising model with vacancies. Physica A: Statistical and Theoretical Physics, 108(2-3), 589-597. https://doi.org/10.1016/0378-4371(81)90153-9