This question was asked so many times in this forum.

Making the cell value as reference then it requires Indirect() function.

Without using Indirect() function we can't make the cell value as reference.

But Indirect works with open workbook reference only. Indirect wont work with closed workbooks.

So, if you want to reference it to the closed workbook then you can use Indirect.Ext of MoreFunc addin which will work with closed workbook too.

Refer the below link to get Morefunc addin / usage.

http://www.ashishmathur.com/?s=morefunc