Formula without sheet names

Good afternoon,

I have the following formula which works great, but I have to change the worksheet name every time I use it. Is it possible to set up this formula where I don't have to change the worksheet names? Could this formula also be set up as a macro?


=IFERROR(INDEX('[CORVEL_CLEAN_BILLING 051818 after Clearing with Formula.xlsm]CORVEL_CLEAN_BILLING 051818'!$G:$G,MATCH(LEFT(E1286,9),LEFT('[CORVEL_CLEAN_BILLING 051818 after Clearing with Formula.xlsm]CORVEL_CLEAN_BILLING 051818'!$H:$H,9),)),"")

I have also attached the spreadsheets for this formula.