been a while since I was last around - but for that i've brought one big of a treat:
Yes, I know, the file is huge - but its 36 manuals after all.
This means even if you dont have perfect English skills you can still look up important stuff in your native language (if it is one of those 11 other languages they support...).
As for the source and how official they are: they are copies of the original digital EA manuals that came on a CD per BfME Anthology pack.
May these (almost) lost writings help in your endeavours to conquer Middle-Earth, my friends!