Citing a book without publisher

There are a number of related questions (for instance about BibTeX not printing a publisher), but I couldn’t find a prior question quite like mine. Anyway…

Many centuries ago, some books were published without a traditional publisher of the sort common today. I want to cite such a book, and currently use this BibTeX entry:

@BOOK{Ruscelli:66,
       EDITOR = "Gerolamo Ruscelli",
       TITLE = "Le imprese illustri",
       PUBLISHER = " ", 
       ADDRESS = "Venice, Italy",
       YEAR = "1566"
}

Of course when I compile my document I get the following warning message:

Warning--empty publisher in Ruscelli:66

This is not particularly bothersome, but I’m wondering if there is a way to avoid this error without mangling the printed reference entry. I have tried PUBLISHER = "~", but that gives a silly blank "entry" with hanging comma. I’ve tried commenting out the PUBLISHER, but that of course gives an error.

It would be nice to have some form of DUMMY PUBLISHER option so that if a publisher isn’t available, the typesetting goes on as desired.

I’m not eager to altering the core BibTeX code, and am hoping there is some clever workaround that I haven’t found on my own.