"Between 1768 and 1774, he [Pallas] led an expedition to central Russian provinces, Povolzhye, Urals, West Siberia, Altay, and Transbaikal, collecting natural history specimens for the academy. He explored the Caspian Sea, the Ural and Altai Mountains and the upper Amur River, reaching as far eastward as Lake Baikal. The regular reports which Pallas sent to St Petersburg were collected and published as Reise durch verschiedene Provinzen des Russischen Reichs (Journey through various provinces of the Russian Empire) (3 vols., 1771–1776). They covered a wide range of topics, including geology and mineralogy, reports on the native peoples and their religions, and descriptions of new plants and animals" (Wikipedia article on Peter Simon Pallas, accessed 09-2017).
Digital facsimile from the Hathi Trust at this link. English translation as Travels Through the Southern Provinces of the Russian Empire in the years 1793 and 1794. 2 vols. London, 1802-1803. Digital facsimile of the second edition (1812) of the translation from the Hathi Trust at this link.