Need formula for sheet & cell reference
 

Help
Have a list of sheet names and want to create a formula to use sheet name
as a reference in a formula. Have tried "Indirect" but haven't succeeded
with that or any other.
For example

sheet names listed vertically i.e. inv1, inv1, inv3 etc.
formula needed to refer to "sheet name"[Inv1] AND "cell reference"[g10]

Have used SheetOffset in VBA but want to use actual sheet name, rather than
offset.
For this file it is not possible to use consolidation feature.

Will appreciate any help.
TIA
Malcolm Hughes