Stalin is a controversial figure, so the books about Stalin's history are also controversial.

I recommend several books about Stalin to you, some for him, some against him and some neutral.

Support him:

Stalin of Emelianov: the unmodified file, Stalin, the grand marshal of Vladimir karpov.

Against him:

De Volkonov's Political Description of Stalin

Neutral:

Robert? Xie Weisi's Biography of Stalin, Edward Ladinski's Biography of Stalin, Rebas's Biography of Stalin: Fate and Strategy, and Roy Aleksandrovic Maidevijeff's Let History Judge: On Stalin and Stalinism.