There is a “Rule of 7” in research. It states that you can find out anything if you are willing to go seven levels deep. If the first source you ask doesn’t know, ask them whom you should ask next, and so on down the line. If you are willing to go to the 7th source, you’ll almost always get your answer.
Never stop pressing forward at the first roadblock. Keep digging and there is usually a way around or through it.