Hugh Trevor-Roper's "The Last Days of Hitler" is the nearest we have to a primary source in English. The 1947 edition didn't have any details from the Soviets,

Hugh Trevor-Roper's "The Last Days of Hitler" is the nearest we have to a primary source in English. The 1947 edition didn't have any details from the Soviets, but there were a number of subsequent editions where additional details were added, most recently 1995.