Right - I'm finding the flawed Deep Research tools useful already, but what I really want is much more control over the sources of information they use.
Sadly I think that’s why non-open source commercial deep (re)search implementations are going to be largely useless. Even if you’re using a customized end point for search like Kagi, the sources are mostly garbage and no one except maybe Google Books has the resources and legal cover to expand that deep search into books, which are much better sources.