Zacher's enthusiasm started years before he was offered a slot on "Booknotes," making him a rarity in the book world. Of the nearly 110,000 non-fiction books published this year, only 50 will be discussed on "Booknotes." Zacher's status is even more unusual because his book, a 329-pager on two-term presidents, was self-published, so he didn't have a public relations machine hawking it.