LibreCalc: select from different sheets

I have three sheets 1,2 and 3. There are three columns on sheet 2 and 3: name (A), surname (B), age(C). How can I select men whose age is >=30 from sheet 2 and 3, order them by age and show resule them on sheet 1 (also 3 columns)? I mean something like SELECT name,surname,age FROM sheet2,sheet3 WHERE age=>30 ORDER BY age and show result on sheet 1.