Oh... That's a very strange topic indeed. I can't even start to think why you need to know where those "extra" words come from. Except for some scientific or linguistic matter.

As for the additional words... They're there because Russian and English language are quite different in many cases. What sounds well in one language will often sound absolutely non-sensical in the other, that's why there is a lot of re-phrasing when translating. In the end what does it matter which words exactly did you use to convey meaning... as long as the meaning is the same?

Just don't start talking about how that might fail to carry over all or some of the subtleties the original may have had. Hell, even a direct literal translation tends to do just that more often than not. This is where your translating skills really shine. Interpreting a phrase while taking into account subtle shades of meaning and transform it into another form without losing anything is a real work of art. So you gotta be flexible, man.