Both are topics of some books now cheap in Kindle form.
The Dinosaur Hunters: A True Story of Scientific Rivalry and the Discovery of the Prehistoric World (Text Only Edition) by Deborah Cadbury (previously published under a different name, I think) may be a bit esoteric for some, but for a dollar-ninety-nine …
The story of two nineteenth-century scientists who revealed one of the most significant and exciting events in the natural history of this planet: the existence of dinosaurs. In `The Dinosaur Hunters’ Deborah Cadbury brilliantly recreates the remarkable story of the bitter rivalry between two men: Gideon Mantell uncovered giant bones in a Sussex quarry, became obsessed with the lost world of the reptiles and was driven to despair. Richard Owen, a brilliant anatomist, gave the extinct creatures their name and secured for himself unrivaled international acclaim.
The Guns of August: The Outbreak of World War I; Barbara W. Tuchman’s Great War Series (Modern Library 100 Best Nonfiction Books) by one of the great earlier popularizers of history Barbara Tuchman:
In this landmark, Pulitzer Prize–winning account, renowned historian Barbara W. Tuchman re-creates the first month of World War I: thirty days in the summer of 1914 that determined the course of the conflict, the century, and ultimately our present world. Beginning with the funeral of Edward VII, Tuchman traces each step that led to the inevitable clash. And inevitable it was, with all sides plotting their war for a generation. Dizzyingly comprehensive and spectacularly portrayed with her famous talent for evoking the characters of the war’s key players, Tuchman’s magnum opus is a classic for the ages.
And not on sale, but I’m putting it here because you may want to read it: All Quiet on the Western Front: A Novel by Erich Maria Remarque. If you don’t know the book, you should. Also a great movie.