Inport from a variable file name

I have a sheet that I need to import information from a separate file, however the separate file is saved under a different name each time. More specifically it is an invoice that is saved under the project number (ex: 06252.xls), on the spreadsheet I need to import certain cells based on the project number which is in column A of the spreadsheet. I can use the "lookup" function to import opposite of what I would like (spreadsheet to invoice, vs invoice to spreadsheet) however the boss says that he would prefer it the other way....ugh. I'm not sure if it is possible, but if anyone has any suggestions of a good way to do this I would appreciate it.

I found what I needed...thanks anyhow