Nikolay Antov, "The Ottoman “Wild West”: The Balkan Frontier in the Fifteenth and Sixteenth Centuries" English | ISBN: 1107182638 | 2017 | 345 pages | PDF | 7 MB
Violence in the Hill Country: The Texas Frontier in the Civil War Era by Nicholas Keefauver Roland 2021 | ISBN: 1477321756 | English | 288 pages | PDF | 4 MB
Big Thicket people : Larry Jene Fisher's photographs of the last southern frontier By Fisher, Larry Jene; Hunt, C. E.; Sitton, Thad; Fisher, Larry Jene 2008 | 140 Pages | ISBN: 0292717822 | PDF | 77 MB
Louis Fairchild, "The Lonesome Plains: Death and Revival on an American Frontier" English | 2002 | pages: 346 | ISBN: 1585441821, 1623497876 | PDF | 2,7 mb