Railroad Archives Online
- CollectionE0480 - Great Northern Railway Historical Society Clearance Diagrams
- Series003 - Great Northern Railway Company (U.S.)
- Subseries Level 1009 - Engineering Records
- Subseries Level 2008 - Physical plant drawing
- Subseries Level 3007 - Track
- ItemDakota Division - Great Northern Railway Dakota Division Clearance Diagram, 1957-1969
- ItemMesabi Division - Great Northern Railway Mesabi Division Clearance Diagram, 1957-1969
- ItemMinot Division - Great Northern Railway Minot Division Clearance Diagram, 1957-1969
- ItemWillmar Division - Great Northern Railway Willmar Division Clearance Diagram, 1957-1969