All the books written by Leonard Read, founder of the first recognizable modern libertarian educational institute, the Foundation for Economic Education (FEE), are now fully digitized and available at FEE's website. "The Complete Works of Leonard E. Read" project includes 36 books, including his pre-FEE first foray into free-market, anti-New Deal thought, The Romance of Reality.
This essay by Jeffrey Tucker announcing the availability of all these books (most composed of essays he wrote for FEE's flagship magazine The Freeman) is a nice introduction to where Read came from and what he tried to achieve. Links to all the individual books are also at that link.
Tucker's summation of Read's role as the apostle of libertarian thought to middle American businessmen and those who worked for them:
His works were pored over by a generation of businesspeople and professionals who so badly needed inspiration in dark times. He provided it with his continuing themes: celebrating human creativity, warning against all forms of control, calling for individual improvement as a path toward freedom, eschewing politics as a workable solution, and pursuing the path of peace in all aspects of life.
Read wrote the magisterial "I Pencil" which is to my read (and Milton Friedman's) likely the most insightful works of popular economic thinking ever written, explaining the dizzying and wild possibilities that free trade and the division of labor bring to not just fruition but profusion.
Read also came up with what I think is the best slogan-level summation of the true libertarian spirit: the acceptance and allowance of "anything that's peaceful."
Read's history and significance to the modern American libertarian movement is told at length in my book Radicals for Capitalism: A Freewheeling History of the Modern American Libertarian Movement