Before these brilliant expositions, Minkowski's pioneering writings were accessible only to specialists. This classic two-volume work focuses primarily on geometric problems involving integers and algebraic problems approachable through geometrical insights. It demonstrates the simplicity and elegance of number theory proofs and theorems and illuminates many other algebraic and geometric topics.
Here's a sample of other books in this Dover category
Geometry of Complex Numbers by Hans Schwerdtfeger Illuminating, widely praised book on analytic geometry of circles, the Moebius transformation, and 2-dimensional non-Euclidean geometries.
Number Theory by George E. Andrews Undergraduate text uses combinatorial approach to accommodate both math majors and liberal arts students. Covers the basics of number theory, offers an outstanding introduction to partitions, plus chapters on multiplicativity-divisibility, quadratic congruences, additivity, and more
The Beauty of Geometry: Twelve Essays by H. S. M. Coxeter Absorbing essays demonstrate the charms of mathematics. Stimulating and thought-provoking treatment of geometry's crucial role in a wide range of mathematical applications, for students and mathematicians.