user: Question: What are the notes regarding the Scout X-4 vehicle which ceased operation in June 1971?
Columns: ['Name', 'Launched', 'Vehicle', 'Ceased operation', 'Notes']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['Injun 1', 'June 29, 1961', 'Thor-Able', 'March 6, 1963', 'Failed to separate from Solrad 3; still in orbit']
SQL:

assistant: SELECT "Notes" FROM "Table" WHERE "Vehicle" = 'Scout X-4' AND "Ceased operation" = 'June 1971';