Conditional sum w/multiple criteria using cell references

Hello everybody.
I'm aware of a conditional formula to make a sum based on multiple criteria. This to include only a manually entered list of text strings. In this case, I'm only interested in Jessica's and Paula's sales figures:

= ( SUM( SUMIFS(C2:C100; A2:A100; {"Sales"}; B2:B100; {"Jessica";"Paula"} ) )


The big limitation of this formula is exactly the fact that you can only insert the list of the salespersons directly into the formula. It doesn't allow any cell reference to the list. So in case I have a long list and I want to "flexibilize" it using cell references, this formula won't help.

Is there any other formula that will?

Thanks for trying oteixeira.
But that's a relatively basic way to do it. I intend on using a more versatile and compact method.

Reason being:
1) I like my spreadsheet nice and tidy, with the fewer number of cells and calculations as possible.
2) I'm looking forward to evolve from that (possible) formula, so I can later on combine "include" and "exclude" criteria. This is another subject, though.

Worked beautifully, oteixeira.
And by doing some tweaks, the formula even allows to combine an "exclude" criteria using cell references.

Thanks a lot!