Search by (lack of) publisher?

Is it possible to search the wiki specifically for characters with no listed publisher? If so, how?

I'm doing an art project that uses a lot of characters from DC publications, many of them from older comics. Step one of this project, the set up, took the form of searching for characters by publisher and then going through and making an external list of what characters I wanted to use. Step two is where I encountered this issue, though. Step two has me pick a character and read most every comic that they're in. As I'm going through, though, I am also looking at the other characters from those issues, and I discovered that more than a few of them have (had, now) no publisher listed at all. Some of those characters would have been on my list if they had been in my search, so I wanted to know if there was a way to search specifically for characters in that situation.

@brvtvs: There isn't unfortunately.

@pikahyper: I guess I'll have to go through the issues as I reach one of the characters in them and backtrack to include them later then. Thank you!