how to sum multiple worksheets in a single sheet?

i tried using
=SUM(INDIRECT("'"&$I$1:$J$1&"'!i5"))

where i1 and j1 is the name of the worksheet and i5 is the value present in the all the different worksheets. Now i want that if i will the drag the cell downward and it will show i6,i7,i8 respectively..it should cells ref automatically.