References

Additional sources and materials

Bukharin, M.D. 2014: [New Documents on the History of Exploration of Eastern Turkestan]. Vestnik drevney istorii [Journal of Ancient History] 3, 163–183.  
Bukharin, M.D. 2015: “Wissenschaft ist nach meiner Meinung nur ein anderer Ausdruck für Humanität…”. Letters of A. Grünwedel to V. V. Radloff from the Collection of the Archives of the Russian Academy of Sciences, St.-Petersburg Branch. Berliner Indologische Studien. 22, 7–47.
Hopkirk, P. 1990: The Great Game. On Secret Service in High Asia. Oxford.
Karber, Ph. 2015: Postmarks from a Political Traveler. New York.
Tamm, E. 2013: The Horse that Leaps Through Clouds: A Tale of Espionage, the Silk Road, and the Rise of Modern China. Vancouver–Toronto–Berkley.