All the books at the top of the list were free. Some of the factors that can potentially determine what's at the top of the list are most downloaded, most stars, and relevance to the search term "history." The list also seemed to favor newer books over older books, or at least books with covers tend to be higher on the list. Books over 90 years old in the public domain almost never have covers. Six years ago, the latter were pretty much the only free books available. As for accuracy, what's most relevant is frequency of downloads and highest rated reviews. Therefore, Newport Tower Unsettled History being high on the very long list would suggest that at least a significant portion of the population found the book persuasive. Lastly, there's the question of what gets classified as fiction and what gets classified as non-fiction. Categorizing books incorrectly alienates readers. If you worked for Barnes & Nobles or Amazon, how would you classify the books discussed ITT? Would you put them in the fiction or non-fiction sections?