user: Question: Which viewers have the language of troff (typesetter runoff) , groff (GNU runoff)?
Columns: ['Language', 'Creator', 'First public release date', 'Editor', 'Viewer']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['Computable Document Format', 'Wolfram Research', '2010', 'Mathematica', 'CDF Player']
SQL:

assistant: SELECT "Viewer" FROM "Table" WHERE "Language" = 'troff (typesetter runoff) , groff (GNU runoff)';