This book, like the rest by Sprech Media (SS Panzer - SS Voices, The Last Panther, Tiger Tracks) is a piece of fiction.
There's just too many details that point to that - from the utter and complete lack of sources or identifiable unit numbers (that could have led to verifications of facts) to technical and historical mistakes (for instance, the IS-3 tank appearing in a 1943 story) it's quite evident that this is not a collection of "eyewitness accounts" but merely a work of a very excitable imagination.
Other, often repeated details give that away - the fact that from what's written 9/10 soldiers killed in WWII were decapitated (really, everything, from a single bullet to a naval shell to a 60-ton tank falling on you scenes are filled with severed heads; heads on the snow, heads on tanks, heads on tree branches, you name it), experiences that the narrator absolutely could not have seen (from a complete overview of a battle through the driver's slit to a -obviously weapon systems exprt- civilian at the cellar of her home), sub-stories that read like out of a bad Hollywood script (the beautiful Russian prisoner who travels chained in the tank -like there's room for it there- or nurses exchanging sexual favors for cigarettes) - EVERYTHING about these books point to someone contemporary who has read up quite a bit and then fabricated some rather sick fantasy.
Stay away!