Assuming you need the integral expressing the volume of 
, the easiest setup is to integrate with respect to 
first.
This is done with either
Thanks to symmetry, integrating with respect to either
or 
first will be nearly identical.
First, with respect to:
Next, with respec to:
This is done with either
Thanks to symmetry, integrating with respect to either
First, with respect to
Next, with respec to