In the standard edition of the Tanya, the Mare Mekomot are not given accurately, e.g Avot Person 2, Nidda Peek 5. Is there a way to reach accurate Mare Mekomot?
There is a set of sefarim that give very detailed notes, etc, including sources. You can see the first volume here on hebrewbooks (all the volumes are there). It is called:
"לקוטי אמרים תניא (בצירוף מ"מ, ליקוטי פירושים ושינוי נוסחאות)"
Also, the Lessons in Tanya probably have the footnotes you're looking for as well: