I'm reading Methods of Modern Mathematical Physics, v. 2, Sec. X.7, about quantum field theory. After the proposition at page 227, where they define an interacting hamiltonian with a cut-off, they mention that it is possible to remove the cut-off by choosing a new representation, and that they will explain it in chapter XIX, but it seems that this chapter does not exist in the whole series of books.
Have they written this chapter somewhere else?
Where can I find more information about this topic, from a mathematical perspective?