The Bear Went Over The Mountain: Soviet Combat Tactics in Afghanistan is a good, detailed, but admittedly slightly dated (I think originally it's from 1993 or something, there is a 2013 edition with some updates) military history and operational and tactical analysis of the Russian efforts in Afghanistan, made up largely of vignettes by Russian personnel on the ground as well as expert analysis of their experiences. It's compiled and translated by Lester Grau, an American staff officer, from a report originally put together by Soviet staff officers, and the 2013 edition also has some work from David Glantz, a giant in the field (best known for Stumbling Colossus: The Red Army on the Eve of World War and other detailed military histories of Soviet forces in WWII and beyond). There is a companion book called The Other Side of the Mountain, also by Grau, that covers the same topics from the mujahideen perspective. Even 20 years later, these are still regarded as some of the best military histories and analyses of that war.

'Afgantsy: The Russians in Afghanistan 1979-89,' by Rodric Braithwaite. This is probably the most obvious choice.