Copy formula BUT change spreadsheet Name

Hi,

I have a totals spreadsheet which contains copied formulas but I have to individually change the spreadsheet reference.
How can I auto change the spreadsheet reference but keep the formulas?

The spreadsheet names are months/dates (i.e. JAN15, FEB15, MAR15, APR15 & so on)
The Formula I'm using is like this:

JAN15 TOTALS (CELL B17)
Column C/ROW 18........
='JAN15'!$G$2+'JAN15'!$G$14+'JAN15'!$G$26+'JAN15'!$G$38
Column C/ROW 19.........
='JAN15'!$G$3+'JAN15'!$G$15+'JAN15'!$G$27+'JAN15'!$G$39
Column C/ROW 20.........
='JAN15'!$G$4+'JAN15'!$G$16+'JAN15'!$G$28+'JAN15'!$G$40

IN FEB15 TOTALS (CELL C17)
Column B/ROW 18........
='FEB15'!$G$2+'FEB15'!$G$14+'FEB15'!$G$26+'FEB15'!$G$38
Column B/ROW 19.........
='FEB15'!$G$3+'FEB15'!$G$15+'FEB15'!$G$27+'FEB15'!$G$39
Column B/ROW 20.........
='FEB15'!$G$4+'FEB15'!$G$16+'FEB15'!$G$28+'FEB15'!$G$40

It goes right through to DEC15.... I want to know how to copy the formula across but have the spreadsheet name change.
March totals collected from March Spreadsheet
April totals collected from April Spreadsheet & so forth.

1st, make sure that ALL your row headings match. For instance in Totals2 A5, you have "NV FOLLOW UPS", but in the Month tabs for the same thing, you have "NV " (Note the extra training spaces)

Once you have fixed that, you can use this, copied down and across...
=SUMIF(INDIRECT("'"&LEFT(B$3,3)&"14'!A2:A43"),$A4,INDIRECT("'"&LEFT(B$3,3)&"14'!G2:G43"))

For 2015, change the bolded part from 14 to 15

Just out of curiosity, which 1 worked for you?