Searching for a Red Army junior officer

TL;DR: Where to find personnel records for the Red Army's 3rd Shock Army, 79th Rifle Corps.

A somewhat removed family relation (she's my mother's second cousin) is trying to find her family's origin, specifically her now deceased father's. Her father always boasted that his brother had been there when Hitler's body was found (which as you might imagine nobody took seriously) but she tells me a friend showed her a book on the subject with mention of a lieutenant of the correct last name and a superior officer by the name of Klimenko.

I couldn't find information on the lieutenant but Klimenko seems to be Lieutenant Colonel Ivan Klimenko, Smersh chief of the 79th Rifle Corps (3rd Shock Army) which Elena Rzhevskaya's account of the finding of Hitler's body designates as the commanding officer on site.

So assuming that my (second aunt? who knows)'s father didn't just read about it at some point and happened to share the last name I'd need to find personnel records for the 79th Rifle Corps and it's subordinate units, does anyone know where or how that could be done?