auto increment worksheet while copying

How do make an auto increment of worksheet while copying?

example:

if i copy one cell(A1) by dragging the mouse, this will be the result:
(B1 is the worksheet)
Cell -----> Formula
A1 -----> =SUM('B1'!$E$3:$E$14)
A2 -----> =SUM('B1'!$E$3:$E$14)
A3 -----> =SUM('B1'!$E$3:$E$14)
and so on...

the result i want is like this while copying by dragging:

Cell -----> Formula (B1 is the sheet)
A1 -----> =SUM('B1'!$E$3:$E$14)
A2 -----> =SUM('B2'!$E$3:$E$14)
A3 -----> =SUM('B3'!$E$3:$E$14)
and so on...

Need some guidance.. thanks

thanks a lot, it works out fine.