CRon help

Not exactly Oracle specific, but I know many of you know the answer to this I imagine...
How can I schedule a cron job to submit a job on the thurd Sunday of every month.

I took at a stab at it thusly:
00 8 15-22 * 0

But now I realize that is an OR condition and so jobs every sunday and on the 15-22 are getting submitted instead of just every sunday that falls on the 15-22.

Any help/inisight appreciated!!

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David



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