Since this primer came out in 1989, the fall of the USSR has led to much more knowledge of the details of the Red Army and its organization. As with any work in this series it is not intended as a definitive study, but an introduction. As such, it still is useful. As it was done before the end of the Cold War, much source material, even though published in prior years, has become available, and such publications as the now defunct English edition of Militaria and the still active French edition of Militaria have given us much more detail than is possible herein but that requires a large investment for the merely curious.
So, start here and then go on to the photo studies and reenactments with living models so prevalent in recent years.