Indirect reference

I have a file .xlxs with several sheets - each sheet with its own name (of course) - and I need to reffer to these sheets through a formula, but I need to use the content of a cell to compose the formula and access data on these sheets.

It's not so clear, so I'll give an example:

- Main sheet (called "Panel") with column F containing the tickers of actives (stock market)

- Several other sheets (one for each ticker with data I need to access) named after the ticker

So, I have in sheet Panel cell F10 the ticker PETR4 and, also, a sheet named PETR4.

How can I access data on sheet "PETR4" by using the content of the cell F10?

Today I do it "manually" by typing =PETR4!C3. I'd like to replace the text PETR4 with a formula to get the value PETR4 from the cell F10.

Thanks, and I hope I was clear enough (considering english is not my native language...)