Emmis, Radio One and Entercom are basically "pure play" radio companies. Though he worded his question a bit awkwardly, I think what he is looking for are publicly traded company who are primarily known for OTHER lines of business, but who happen to own some radio also.
This may have been a bit more common in earlier days than it is today. Insurance companies, funeral homes, retailers like Sears and other companies better known for their other lines of business were also radio owners.
There were probably more businesses that were NOT publicly held that were crossover owners.
Here is a "wild guess" from an accounting point of view why there are not a lot of publicly held "not-primarily-broadcasters" companies today in the radio business. Public companies do not like to own a lot of assets. They don't OWN their buildings, they rent them. They don't OWN their trucks, they lease them. Here is the reason why: If you can keep your invested capital LOW, then your earnings/profit per dollar invested is quite high. In radio, to own a station, you pay a lot of money for the "blue sky" perceived "franchise" value. The way Wall Street analyzes earnings on investment, it looks like a bad investment. You can't rent the "blue sky franchise value".... you can't sell it to someone else and let them lease it back to you.
I know, there are LMAs, etc, but the accountants in the America that lives and dies by Wall Street put radio into their computers, and for the most part it come out: TILT! or GAME OVER!