Change reference "name" in formula to value inside other cell

Hi guys,

Sorry for the not so flattering title of my issue, I simply do not know how to put it in short term.

My issue is:

I have an sheet with an overview.
It is like this in format:

1 2
A Doc. no. Amount (Reference to another sheet)
B Doc. no. Amount (Reference to another sheet)
C Doc. no. Amount (Reference to another sheet)

It is looking into another sheet to find the amount of a deal. I have been doing this manually - stupid, I know

All sheets are named a Doc. no. that matches the Doc. no. in the overview.

Now, my VLOOKUP forumla looks like this: =+VLOOKUP(G4;'50025041'!B24:D119;3;FALSE)
Working great - no problems.

BUT.. I would like to change the red number, so it points to A1 instead. Is it possible to do so in an easy way?