Counties Located within a PUMA

I'm looking for a list or data source for counties located within a PUMA.  I have a list of the name of the PUMAs, and this often contains the counties, but not always. an example:

GEOID PUMA BASENAME NAME
2800500 500 Three Rivers Region––Lee, Pontotoc & Union Counties––Tupelo City Three Rivers Region––Lee, Pontotoc & Union Counties––Tupelo City PUMA
2800600 600 Golden Triangle Region––Starkville, Columbus & West Point Cities Golden Triangle Region––Starkville, Columbus & West Point Cities PUMA
2800700 700 North Central Region North Central Region PUMA

Here, clearly PUMA 500 contains Lee, Pontiac, & Union Counties, but it's impossible to find out from this description which counties are in PUMA 600, The Golden Triangle Region, or PUMA 700, the North Central Region.

Any help is greatly appreciated.