SUMIFS with "array OR" and cell reference

Hi all. Been a while since I was on here but hoping someone can help me tackle this.

I have data than I would like the sum of revenues for in a chart based on if it matches a customer name and falls within one of three months. I have done this successfully by manually entering the months into the array portion of my sum+sumifs formula, but I would like instead to reference cells which I have set to update since I would rather not have to change the formula every three months. Current formula is as follows:

=SUM(SUMIFS(RAW!$AN:$AN,RAW!$T:$T,$A11,RAW!$C:$C,{"2012 / 11","2012 / 12","2013 / 01"}))

So instead of using the "YYYY / MM" I'd like to simply reference a set of cells containing that data. Possible?

Thanks in advance.

Also, I do know I could simply combine 3 SUMIFS statements, but I'd rather the more elegant solution.