For Kazan's role in shaping Tatar identity, Daniel R. Brower's Russia and Asia: Encountering the Russian Empire has the best concise English treatment of the Tatar–Russian encounter and the Kazan Khanate. Travellers interested in the wider Tatar world will find Azade-Ayse Rorlich's The Volga Tatars: A Profile in National Resilience the standard modern history of how the community survived from the 1552 conquest to the present.
For atmosphere, Anna Vasilyeva's Kazan: A Walking Guide is a small bilingual book sold at the city tourist office that puts the streets and buildings of the old centre into context better than any general Russia guide. In fiction, Gabdulla Tukay, the Tatar national poet, has a slim Selected Poems in English translation from the Kazan Academy of Sciences press — at least one of his poems is sold in every Kazan bookshop and the lives of every Tatar schoolchild starts with him.
For a foreign-traveller's view, Colin Thubron's Among the Russians has a memorable Kazan chapter from his 1980s drive across the Soviet Union — still readable, still recognisable.