This method will work on and for any subject.
1. Site your sources. Know what speaks to you by connecting with the events expressed. If you don't see the connection, it doesn't mean you ought to give up. It just means, try looking somewhere you haven't before, but likewise, that may be known to you or someone you know for answers. One secret about truth is that it will always reveal itself to you, no matter what. So use it as a guide.
2. How do you spot truth. Through passion, facts and actions.
3. How do you spot alternative truth? Some call this direct dishonesty or manipulation, changes in what's known. All you need to do is remember to piece together a timeline if you can, when searching for the truth about a specific place in time. Otherwise, if you are searching for truth about how something works, as in a theory, always test what you have pieced together as a concept first.
A common misconception about truth, is that evidence can be faked. Although this is real in a very manipulated appearance like sort of manner, the way evidence is presented cannot be faked. There in lies the truth and proof of all you seek for, for it is real and always within reach. You just have to find the right tool to access it. What you find is what you get, always.