Summary of data from multiple worksheets

Hi,

Apologies for the relative simple nature of my query. I have 9 sheets of sales data, some with over 50,000 records. I need a way to present this information in another worksheet so I can bring up just the data based on individual brands. I understand a pivot table is needed however I cannot see how to gather data from multiple worksheets.

For example, I need to look at all the different sales for Product A, which appears in multiple worksheets. Product A is broken down to store-level, with records for number of sales in each store, one record for units and one for value (for the same store and product). Is there a way I can get the data for all of Product A in one worksheet so I can then easily add the totals across all stores by both units and value?

E.g.
Store 1 - Product A - 10 units
Store 1 - Product A - £20
Store 2 - Product A - 7 units
Store 2 - Product A - £14

Many help much appreciated, or if you can direct me to somewhere that can help that would be great.