Pádraig Murphy at The Dublin Review of Books:
There is a very rich memoir literature covering Stalin’s life and times, written after his death by those centrally involved. The most prominent part of these works are the memoirs of Stalin’s daughter, Svetlana Alliluyeva. Like all memoirs, these sources have to be treated carefully – self-interest or failing memory affects all of them, although it is accepted that Svetlana’s memoirs are in a separate class in this regard. After the fall of the Soviet Union, many Russian archives relating to the Soviet period were opened, providing new material on that period, and in particular on Stalin himself. These lives of Stalin and his entourage draw on this, as well as drawing carefully on the memoir literature.
In Oleg Khlevniuk’s view, too many sources for biographies of Stalin have been made available over the last twenty years, if one bears in mind the need to sift their sheer volume. In his words, the dilemma consists either of covering the hero without the context, or the context without the hero. He emphasises that many of the documents on which Stalin worked directly are in the former archive of the politburo, now the Russian Presidential Archive, which has not yet been completely opened to researchers. Pending such opening, perhaps a fully definitive biography cannot yet be written. For the time being we’ll have to content ourselves with the results of research on the documentation available, of which these are the most notable.
more here.