With Pen and Paper on the Frontier in 1851: The Diary and Sketches of Frank Blackwell Mayer, plate prior to p. 19. Minnesota Historical Society, St. Paul (1932).
Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (70 years p.m.a.), Mainland China (50 years p.m.a., not Hong Kong or Macao), Germany (70 years p.m.a.), Mexico (100 years p.m.a.), Switzerland (70 years p.m.a.), and other countries with individual treaties.
{{Information |Description=Genre artist Frank Blackwell Mayer |Source=''With Pen and Paper on the Frontier in 1851: The Diary and Sketches of Frank Blackwell Mayer'', [http://memory.loc.gov/cgi-bin/ampage?collId=lhbum&fileN