On Line catalog: Personal Accounts and Primary Sources at the Minnesota Historical Society Organized by regiment and unit; compiled and introduced by Stephen Osman.
MHS Civil War online research page
Books
Brackett “Thrilling and Fatal Adventures of Messrs. Brackett and Freeman” in Heard, Isaac V. D. History of the Sioux War and Massacres of 1862 and 1863 p. 313-320 (1864) contained in free e-book
Hill, Alfred J. History of Company E of the Sixth Minnesota Regiment of Volunteer Infantry (1899) free e-book
Potter, Theodore Edgar The Autobiography of Theodore Edgar Potter (1913) free e-book
Wilson, Horace B., 6th Minnesota Company F Reminiscences of the Indian War of 1862 (1886) free e-book
A Thrilling Narrative of Indian Captivity: Dispatches from the Dakota War of 1862 