user: Question: What reference, written by Nelson Riddle, suggests 2 violas?
Columns: ['Reference', 'Author', 'Section Size', 'Violins', 'Violas', 'Celli', 'Basses']
Types: ['text', 'text', 'text', 'real', 'real', 'real', 'real']
Sample row: ['"Arranged By Nelson Riddle"', 'Nelson Riddle', '12 players', 8.0, 2.0, 2.0, 0.0]
SQL:

assistant: SELECT "Reference" FROM "Table" WHERE "Violas" = 2.0 AND "Author" = 'Nelson Riddle';