Google Docs, Spreadsheet name lookup

[Dave]

Hello -

I am working on a Google Docs Spreadsheet to use as a time sheet for my staff.
The plan is that each staff person would be have their own workbook
and within that workbook, each sheet (tab?) would contain data for a given pay period. Each sheet would do a look up to the previous sheet to obtain updated sick / vacation time used.

Ideally each sheet would be named as the date of the start of the time period.

Can anyone give me a formula that will automatically calculate the name of the prior spreadsheet (I know how to calculate dates, etc) what I am hoping for is something along the lines of:


A1 = 6/21/2012
B2 ='A1'!C3
(Where B2 gets the sheet name defined in A1 and then looks up value C3 from that sheet.)

I know I can do "='sheet_name'!C3" to get a value form "sheet_name"
but how can I get the same value if "sheet_name" is calculated (or hardcoded)
in another field?

Thanks in advance!

Dave