Apparently, Parley P. Pratt wrote a book called, "A Voice of Warning" first published in 1937. First editions are rare, even rarer than a first edition Book of Mormon. The article,"One of the Rarest of the Rare Mormon Antiquarian Books on eBay for the First Time," claims most collectors have never even seen one and only three have been offered for public sale in the last twenty years.
The price tag is $75,000. But, "[s]hipping is free as they plan to hand-deliver the book anywhere in the world no extra cost." If that is a little beyond your price range you can buy a technically accurate reprint of it from Experience Press. Experience Press sells other reprints of Mormon classics including first edition Book of Mormons.
But if you just want to get a good look at the current offering of "A Voice of Warning" the article instructs you to access a link off of Wikipedia. So, check out this significant book for yourself.
Those claiming that Parley P. Pratt was an Apostle of Jesus Christ will point out that A VOICE OF WARNING was the first book written by an Apostle of Jesus Christ since John the Beloved wrote his Gospel and the Book of Revelations. According to bibliographers Crawley and Flake, "A VOICE OF WARNING is the most significant book in all of Mormon literature after the canonized scripture."I'm wondering if the Crawley and Flake claim is taken out of context. It is hard to believe that it is THAT important, especially when I've never heard of it. Oh well. Learning something new probably won't hurt me.