Computing the Continuous Discretely by Beck and Robins.
Good intro to the interplay of analysis (Fourier analysis and number theory), geometry, and combinatorics.
Chapter 10: Topology grows into a branch of mathematics in Never a Dull Moment: Hassler Whitney, Mathematics Pioneer by Keith Kendig**
Zeros of Entire Fourier Transforms by Dimitar Dimitrov and Peter Rusev
A long paper/short book on identifying polynomials and entire functions that have only real zeros and the influence of and applications to the Riemann hypothesis.
Learning Modern Algebra From Early Attempts to Prove Fermat's Theorem by Cuoco and Rotman.
Möbius and his Band: Mathematics and Astronomy in Nineteenth-century Germany edited by Fauvel, Flood, and Wilson.
A compilation of articles:
A Saxon mathematician by John Fauvel
The German mathematical community by Gert Schubering
The astronomical revolution by Allan Chapman
Möbius's geometrical mechanics by Jeremy Gray
The development of topology by Norman Biggs
Möbius's modern legacy by Ian Stewart
I had known of Möbius chiefly through the Listing-Möbius band, linear fractional transformations, and the Möbius function and inversion--all of continuing significance in modern mathematics. The articles cover more and provide a nice entre/appetizer for modern topics.