Unless you want to go the VBA route to work out the Tab name, the Excel formula is fairly ugly based upon Mid functions, etc. But both these methods can be found here if you want to go that way.
Rather, the way I would do it is:
1) Make one cell on your sheet named, for example, Reference_Sheet
and put in that cell the value "Jan Item" for example.
2) Now, use the Indirect
function like:
=INDIRECT(Reference_Sheet&"!J3")
3) Now, for each month's sheet, you just have to change that one Reference_Sheet
cell.
Hope this gives you what you're looking for!