First of all, I echo the comments that recommend consulting a research librarian. They are professionals who are experts in finding information like this.
As far as what you can do yourself, I recommend combining two fundamental literature search strategies: synonym searching, and then forward and backward citation searching. Warning ahead: both phases involve a lot of work, since your scenario is non-trivial.
Phase 1: Synonym searching: The idea here is to search for as many synonyms as possible of your two key concepts. Here is the general procedure:
- List all the synonyms you can for each of the two concepts. In your case, that means to list all the synonyms you can for crime, and all the synonyms you can for Gutenberg press. Using a standard thesaurus (e.g. thesaurus.com) could help here.
- Search in each database for every possible combination of every synonym. Yes, that means that if you have d databases, and c synonyms for crime and g synonyms for "Gutenberg press", you will do dcg keyword searches. Yes, that's a lot, but it's not over yet.
- In each article that you uncover that you consider valid, examine the paragraph that defines the concepts (crime and Gutenberg press in your case) and see if these descriptions offer more valid synonyms that you didn't think of initially.
- Repeat the searches with all possible combinations of any new synonyms that you uncover.
- After doing all this, if your keyword searches did not uncover any of your initial personal list of articles that you know to be relevant, then carefully try to understand the shortcomings of your keyword searches.
- Based on your new understanding, revise or extend your keyword list, and repeat the searches.
- Keep on doing this until you come up with nothing more new.
- Prune the list to remove duplicate articles.
Phase 2: Forward and backward citation searching: The idea here is to find all the articles that either cite (forward) or have been cited by (backward) all the articles that you have thus far identified. Here is the general procedure:
- You begin by combining two lists (if you haven't already done so): your initial list of articles that you know to be relevant, and the list of relevant articles you identified from the synonym searching in Phase 1.
- Backward citation search: Examine the reference list of every article known to be relevant. Ideally, you should look up the abstract of each article; practically, you might only look up articles with suggestive titles, since looking up every single abstract would be very time-consuming. Whenever you find any relevant article, add it to your list of articles to be processed.
- Repeat this backward citation search for every new article that you identify to be relevant.
- Continue going backwards in time until you feel that any new article uncovered would be too old to be relevant.
- Forward citation search: Look up in Google Scholar every article known to be relevant (including the ones added from the backward citation search). Examine every article listed to cite each article. Ideally, you should look up the abstract of each article; practically, you might only look up articles with suggestive titles, since looking up every single abstract might be very time-consuming.
- Whenever you find a new relevant article, then go back and do a full recursive backward citation search on it, and also do a full recursive forward citation search on it.
- Continue recursively iterating until no new articles are found.
So that's the crazy, insane way that you could thoroughly do this. Practically speaking, you might run out of steam and simplify some steps, but then your search would not be exhaustive, so that is your scholarly decision to make.
Here are two articles that go into further detail on each of these steps:
Finally, if there is a researcher mailing list that you know whose subscribers study related topics, it might be helpful posting a request there as well.