Copying selected data from different workbooks with 1 template

Hello,

So sorry to trouble everyone but i have some questions on excel

Background
I want to copy data, both numbers and text from selected cells from 3 to 4 different workbooks (Excel file A, B, C) into one summary report (Excel File Summary)

so my formula is =[BookA.xlsx]Sheet1!$B$4
which work pretty well, i can send out the excel without losing the data.

Question
My question is i have a few more summary reports to do, and the data are from the exact same cells (over 50 different cells) but the file name is different.
Is there a formula i could use to change all the file name and maintain the cells?

i.e. right now i am using

=[BookA.xlsx]Sheet1!$B$4
=[BookA.xlsx]Sheet1!$B$5
=[BookA.xlsx]Sheet1!$B$6

is there a way to automate the formula so that the Workbook name changes with only 1 edit?
I tried changing the formula to =[A1Sheet1]Sheet1!$B$4 where A1 is =[BookA.xlsx]
but when i tried to edit =[BookA.xlsx] to =[BookB.xlsx] i got an error message.

Does anyone have any experience with this?

Thanks a bunch in advance and i really appreciate any help at all =)

Cheers
Kagiri