Books like Riddles in mathematics by Eugene P. Northrop

An encyclopedic reference edited by Fields Medalist Timothy Gowers, the Princeton Companion to Mathematics offers nearly 200 essays by leading mathematicians, covering key concepts, historical development, and interdisciplinary impact of modern mathematics.

A collection of mathematical stories and patterns shared by mathematicians John Conway and Richard Guy

Eastaway invites readers to discover how simple arithmetic patterns and geometry reveal hidden order in everyday life, from the way buses queue to the timing of showers, making mathematics both accessible and surprising.

Explore mathematics through a thrilling collection of puzzles and problems presented within the metaphorical framework of a maze, making complex concepts accessible and engaging.

Problem-Solving Strategies is a unique collection of competition problems from over twenty major national and international mathematical competitions for high school students. The discussion of problem-solving strategies is extensive. It is written for trainers and participants of contests of all levels up to the highest level: IMO, Tournament of the Towns, and the noncalculus parts of the Putnam competition. It will appeal to high school teachers conducting a mathematics club who need a range of simple to complex problems and to those instructors wishing to pose a "problem of the week," "problem of the month," and "research problem of the year" to their students, thus bringing a creative atmosphere into their classrooms with continuous discussions of mathematical problems. This volume is a must-have for instructors wishing to enrich their teaching with some interesting nonroutine problems and for individuals who are just interested in solving difficult and challenging problems.