Thanks for the info. I found some further info on Yermakov. He had quite interesting career:
http://surfcity.kund.dalnet.se/soviet_yermakov.htm
http://www.cieldegloire.com/015_yermakov_d_v.php
The differences of clock times are quite common is my impression and I´m not sure how precise pilots were with clock times in their combat reports - these may have been very rough estimates (did they have time to watch the clock during the combat and remember it exactly?). Also locations can differ more or less when referring the same combat by both sides. My impression is that it is very rare to find combat reports of both sides corresponding 100 % with each other.
But if I have understood correctly the shooting down of Sarjamo (+ accidental loss of Nissinen) on 17.6.1944 can be credited to 159 IAP although likely candidates are 2-3: Dimitri Yermakov or Medvedev (first name?) and perhaps even Anatoli (?) Ruzin.