user: Question: What is the width for hte truss with a source of Zacher (1994)?
Columns: ['Length feet (m)', 'Width feet (m)', 'Load short tons (MT)', 'Truss type(s)', 'Year built', 'Source (Year)']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['feet (m)', 'feet 6inches (m)', 'short tons (t)', 'Queen post', '1878', 'Landis (1966)']
SQL:

assistant: SELECT "Width feet (m)" FROM "Table" WHERE "Source (Year)" = 'Zacher (1994)';