N4 Government, War, Law, and Regulation
- N40 General, International, or Comparative
- N41 U.S.; Canada: Pre-1913
- N42 U.S.; Canada: 1913–
- N43 Europe: Pre-1913
- N44 Europe: 1913–
- N45 Asia including Middle East
- N46 Latin America; Caribbean
- N47 Africa; Oceania