user: Question: What is the archive of the show that aired on 18April1970?
Columns: ['Episode', 'Broadcast date', 'Run time', 'Viewers (in millions)', 'Archive']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['" Episode 1 "', '21March1970', '24:33', '7.1', 'PAL 2" colour videotape']
SQL:

assistant: SELECT "Archive" FROM "Table" WHERE "Broadcast date" = '18April1970';