Like I ask in title, what is the best way to write formula like this one below. I want sum from all sheets values for Germany (values are in B column)
=SUM(SUMPRODUCT(--(First!A2:A11="Germany"),(First!B2:B11)), SUMPRODUCT(--(Second!A2:A11="Germany"),(Second!B2:B11)), SUMPRODUCT(--(Third!A2:A11="Germany"),(Third!B2:B11)))
What is your opinion?

In Google Sheets you can also use
(Please adjust ranges to your needs)
How the formula works.
We create an array using curly brackets
{}stacking the ranges one on top of the other using semi-columns;even from other sheets like{L1:M9;O3:P7;First!A2:B11;Second!A2:B11}. One can add as many ranges as needed. Even open ranges.The
,1in the end of the formula shows that the very first row will be treated as a header row.Please read more about the QUERY. function