Thank you for your help.
A bit of playing about (and the function you so kindly pointed out) gives =INDIRECT("'" & TEXT(A4,"mmm yy") & "'!$C$3",TRUE)
without the TEXT function it brought in the date serial number, and the sum function is : =SUM(INDIRECT("'"&TEXT(A4,"mmm yy")&"'!$C$6:C40",TRUE))
Many thanks
Bookmarks