Can someone help me write this indirect formula without cell referencing, I can't seem to wrap my head around what I'm doing wrong...

In cells,

B2(file name): 2010_Sold.xlsx
B3(Table Name): January
B4(Column Name): Current Price

And this formula works: =SUM(INDIRECT("'"&B2&"'!"&B3&"["&B4&"]"))

However, Id like to not reference cells in the formula. I've done this within a workbook but cant seem to get it to work when indirectly referencing a different workbook.

So something like this(But I'm obviously not writing it correctly, as im getting a #REF! error):

=SUM(INDIRECT("'"&{2010_Sold.xlsx}&"'!"&January&"["&Current Price&"]"))

How do I write this?