Help with Referencing Different Sheets

Hi Everyone,

I've spent a good deal of time trying to solve a reference problem with no luck. I'm hoping you can help a weary excel traveler.

To start, I have excel workbooks with thousands of tabs calculating a percent change from a stock at two different time periods. I've attached the basic premise of the problem with two examples.

I've managed to write a formula making the calculation in cell N19 across all sheets, no problem there.

My problem NOW comes from writing a formula which references the numbers from N19 across ALL sheets with different sheet names. As you can see in the attached, the sheets have predetermined names. Is it possible to write a formula which will automatically reference different sheets (with names like BNXR.US-m, PVBK.US-m) without having to the manual gruntwork? I would like a formula in "Sheet1", Column B, which will automatically generate the numbers listed.

Thank you so much for advice/help in advance!

I was looking for the first two formulas...thanks so much for your help TMS, it worked splendidly