 Prime Obsession: Bernhard Riemann & the Greatest Unsolved Problem by John Derbyshire, 23 April, 2003
 Ball Lightning: An Unsolved Problem in Atmospheric Physics by Mark Stenhoff, March, 2000
 The Millennium Problems: The Seven Greatest Unsolved Mathematical Puzzles of Our Time by Keith J. Devlin, 15 October, 2002
 Unsolved Problems in Astrophysics by John N. Bahcall, Jeremiah P. Ostriker, 17 January, 1997
 The Riemann Hypothesis: The Greatest Unsolved Problem in Mathematics by Karl Sabbagh, April, 2003
 Erdos on Graphs: His Legacy of Unsolved Problems by Fan Chung, Ron Graham, et all July, 1998
 The Five Biggest Unsolved Problems in Science by Arthur W. Wiggins, Charles M. Wynn, August, 2003
 Old and New Unsolved Problems in Plane Geometry and Number Theory by Victor Klee, Stan Wagon, September, 1996
 Unsolved Problems in Number Theory (Problem Books in Mathematics) by Richard K. Guy, August, 1997
 Tomorrow's Math: Unsolved Problems for the Amateur by Charles Stanley Ogilvy, April, 1992
