The standard file that MS excel saves in is PDF. And while there is no "proper" link format per say. Excel is compatible with most of the standard and most used formats around. You can easily change any file directly in to PDF. buy using either an online file converter or a home one.
The first entry is optional which is the workbook name. The following ones are compulsory--that is, the worksheet's name followed by the cell's address. The format is: [WorkbookName]SheetName! CellAddress
The proper link format for MS Excel is one to be shown in the forat for the microsoft programs. There are many correct forms but the best and most correct form is in this version.