Fuller, Graham E. (2010-08-11). A World Without Islam. Little, Brown (објављено 2010). ISBN9780316072014. Приступљено 2015-10-04. „It was actually the Orthodox Church militant that first stimulated [...] Russian campaigns of conquest to the East, advocating the spread of Christianity into the well-established Muslim Kazan Khanate. Immediately after the conquest the church established a strong institutional presence in the Tatar regions and planned for the forced conversion of its Muslim population to Orthodox Christianity. [...] Despite its establishment of churches, monasteries, and religious institutions in the newly conquered regions, the church was to be frustrated in its goal of imposing Christianity on Muslim turf.”