The issue with non-fiction is that some information may come from the parametric memory, rather than source text supplied to the model. So then the issue is whe

The issue with non-fiction is that some information may come from the parametric memory, rather than source text supplied to the model. So then the issue is whether the model can process the text and summarize the book or is it cheating? Fiction published in the last few months is your best shot, though sure depending on the nature of non-fiction this evaluation can be different (but some things remain the same, like you want it to be faithful/factual and not omit important information)