After Stalingrad: Seven Years as a Soviet Prisoner of War by Adelbert Holl
This describes the author’s capture at the end of the Battle of Stalingrad and his progression via various camps as a prisoner of war eventually returning to Germany in 1950. I found the most interesting part covered the time he spent in the Gulag proper working on the Baikal-Amur Mainline in the Angarstroy camps near Tayshet. As is typical with biographical material like this it just shows the experiences of one person rather than giving a broader context.
The degree of German collaboration with the Soviets is interesting. It seems to be much more widespread than I had really considered, but maybe I should not be surprised.