user: Question: Who were the candidates in the districts that was first elected in 1966?
Columns: ['District', 'Incumbent', 'Party', 'First elected', 'Result', 'Candidates']
Types: ['text', 'text', 'text', 'real', 'text', 'text']
Sample row: ['Ohio 1', 'Tom Luken', 'Democratic', 1974.0, 'Lost re-election Republican gain', 'Bill Gradison (R) 50.9% Tom Luken (D) 49.1%']
SQL:

assistant: SELECT "Candidates" FROM "Table" WHERE "First elected" = 1966.0;