link workbook range

I need to have this formula

=AVERAGE(IF(rngDate>=rngFromDate,IF(rngDate<=rngToDate,
IF(rngAcct=rngAcctCriteria,rngAmt))))

reference the rng of another workbook. rng's Date, Acct and Amt are the rng's that will be remote.
rng's ToDate FromDate and AcctCriteria are local.

Thanks,
Dave Rattigan alias ratman