Variable Cell Reference

Question:
If I want to return a value from a specific cell ie B3 you type in =B3, but in my case the row value is variable and I'm using a Vlookup function to determine the row, so I'm using the formula ="B"&A1 where A1 = the value "8", but in the cell just =B* appears, not the contents of cell B8.

In other words I want a formula to display the value of a specific cell, the column is fixed but the row is variable and is determined by another formula.

solution:
=indirect("B"&A1)



Another example:

=SUM(INDIRECT("'MM'!G"&'BE Summary'!$AZ$2+1+A10):INDIRECT("'MM'!H"&'BE Summary'!$AZ$2+1+A10))

In example above, if cell AZ on tab 'BE Summary" = 10 and cell A10 on current sheet is 2 then the formula become =SUM('MM'!G13:'MM'!H13)
note:  10 + 1 + 2 = 13