Even a great search engine like Google only samples a small proportion of all that exists on the internet.
If the information on Google is limited, look for a search tool that specializes in your topic. Maybe you can find an expert's list of the best sites for your needs, or you might need to use a database that isn't free.
If it's more privacy you are looking for, search engines like DuckDuckGo, Metager, or SwissCows might work better for you.
To break out of the Google box, you can try library databases, ask a reference librarian for ideas, or check internet sites such as those below.
And don't forget, sometimes what you seek might be best found in the library - in a book.