Refer to sheet with indexnumber without VBA

[curious4]

I am looking for a way to refer to a sheet without knowing it's name.
The sheets I want to refer to, are generated by some kind of report builder.
It is not possible for me to use VBA

[JohnTopley]

It cannot be done as you need the sheet name or sheet index.

[curious4]

I know the index, but i cannot find a way to use that without knowing the name

[JohnTopley]

Then I am sure VBA is the only option.

[tim201110]

I know the index

can you use macro functions, for example, GET.WORKBOOK()?