1. rec.puzzles (amoeba,, bug, camel, date.dice, monty.and.waldo, mr.s+mr.p, points.on.sphere, spot)

  2. Wolfram MathWorld (angel.problem)

  3. [wu : riddles] (antipodal, cigarettes, code.hack, firing.squad, forcefield.detainment, happy.numbers, lion, prisoners-switch, prisoners.hats, slash.and.dash, submarine, typewriter)

  4. Futility Closet (

  5. Perplex City (domino.dilemma)

  6. The Grey Labyrinth (

  7. Math Olympiad (mark.square)

  8. Rule0/Riddles (pirate)

  9. Judea Pearl. Probabilistic Reasoning in Intelligent Systems: Networks of Plausible Inference. 1988 Morgan Kaufmann. (prisoners)

  10. Car Talk (prisoners-switch)

  11. Problem of the Fortnight, CS at San Diego State University. (square.cut.2)

  12. Martin Gardner. My Best Mathematical and Logic Puzzles. 1994 Dover Publications (termite)