OpenStax
Open Stax: American Foreign Policy 1890 1914: Turner, Mahan, and Roots of Empire
Examines the development of American foreign policy in the latter part of the 1800s, and what Frederick Jackson Turner and Alfred Thayer Mahan did to further American imperialistic interests.
US National Archives
Our Documents: Check for the Purchase of Alaska (1868)
Interactive images of two documents important in Alaska's history: the check written for its 1868 purchase from Russia and the Russian Treaty of Cession (an English transcript is provided), which concluded the deal.