Aggregating Results by Quarter

[bstice]

I have a form that aggregates financial results by month and I would like to be able to total the results by quarter as well. Right now, I use a DSUM function with the accountingperiod as a criteria. Accounting Period comes from a value in a combobox. What would the code look like if I added Q1, Q2, Q3, Q4 to the combobox so that those values caused it total the data for Jan - Mar, Apr - June etc. Here is my current code.
AccountingPeriod = Me.AccountingPeriod

'Consulting Revenue
Me.CR = Val(Nz(DSum("[sumofNet Amount - US]", "SummarizedGLDATA", "[FML Account Code *] = '1111' and [" & field & "] = '" & crit & "' and [Accounting Period *]='" & [AccountingPeriod] & "'"), 0))
CR = Me.CR

Thanks all

Brennan