For example, it is remarkable (in a bad way), that we still cannot do a simple search with a filter. For example, maybe I want to search Luther for "union". One would think it would be as simple as typing
union author:Luther
In fact, 15 years ago, this was already (incorrectly) suggested as the solution to a similar post.
This sort of filtering should also be possible by publisher, year, editor, translator, and every other property.
If I am wrong, and I hope I am, and this is simply a case of undocumented functionality—please enlighten me.