If you are unable to determine the date of publication, simply omit this information. In previous versions of MLA, a placeholder of "n.d." was used to signify "no date," but that is no longer used in MLA 9th Edition.
Often, organizations are responsible for producing and publishing books. Sometimes, there will be two organizations listed - one can be used as the author, and then the publisher might be a separate publishing company. Perhaps more often, an organization will serve as both the author and the publisher of a work. If that is the case, list the name of the organization only once, in the spot for publisher, but do not list an author at all. The entry will start with the title of the source. See the tab "Authors, Editors, Translators, & Publishers" on this Guide for examples.