- Brain-Twisters I
- "Lady or the Tiger" puzzles, a seemingly easy problem in Euclidean geometry, and a dictatorial conundrum involving the reproduction of hermaphrodites.
- Brain-Twisters II
- Brought back by popular demand, yet more of the "Lady or the Tiger" puzzles.
- Brain-Twisters III
- Inheritance problems, bankers who do not all speak the truth, and two simple puzzles in elementary geometry.
- Brain-Twisters IV
- Yet more of the "Lady or the Tiger" puzzles, a variation on one of the geometry puzzles presented last month, and the perils of proofreading.
Revised: June 14, 1999