I have 12 worksheets with different names (I wish, I didn't change names
from Sheet[numbers] *)
I want to perform counta command on column A of each sheet in my reference
sheet.
With a Macro (Given by Gord Dibben) I was able to produce a list of sheet
names in my reference sheet.
Now I dont know how to address these names in counta command. On each sheet
it will be simply: counta(A:A)

Also is there any resources in Internet explaining about dealing with
calculation in different sheets.

*) I think if I leave name of sheets unchanged (Sheet[numbers]) then it will
be easy to use sheet names in commands. Isn't it so?