The following lists, broken into subject and topics, are books that I have read or used to learn certain subjects. I may end up doing book reviews of some of these and if I do I will hyperlink to those pages. If there are books I have not yet read I will make note of that, although I very likely already own it and have browsed in it a bit. So I feel I can vouch for the quality of the text in some way. I've now expanded this list to include general works of fiction and nonfiction, not necessarily just textbooks.
Schaum's Outline of Calculus by Ayres and Mendelson
(Ordinary) Differential Equations
Differential Equations and Boundary Value Problems by Edwards, Penney, and Calvis
A First Course in Differential Equations by Dennis Zill
Ordinary Differential Equations by Morris Tenenbaum
Paul's Online Math Notes Differential Equations (here)
Proofs
Book of Proof by Richard Hammack (can be found here for free from the author) [My review]
Naive Set Theory by Paul Halmos (not really a proofs book, but it certainly helped me learn proof concepts)
Linear Algebra
[Computational and Proof] Elementary Linear Algebra by Stephen Andrilli and David Hecker (I learned proof based LA with this one)
[Computational] Elementary Linear Algebra by Howard Anton
[Proof] Linear Algebra Done Right by Sheldon Axler
[Proof] Linear Algebra by Friedberg, Insel, and Spence
Analysis
Basic Analysis I by Jiri Lebl (can be found here for free from the author)
Elementary Analysis: The Theory of Calculus by Kenneth Ross
Real Analysis: A Long-Form Mathematics Textbook by Jay Cummings
Understanding Analysis by Stephen Abbott
Elementary Real Analysis by Thomson, Bruckner, and Bruckner (treats single, multivariable, and metric spaces. Can be found here.)
Abstract Algebra
Abstract Algebra: An Introduction by Hungerford (a word of warning: this book is unconventional in the sense that it starts with ring theory, develops fields, and then goes into group theory towards the end. Most books do not do this, but I found it more approachable.)
Abstract Algebra: Theory and Applications by Judson (can be found here for free from the author)
Basic Abstract Algebra for Graduate Students and Advanced Undergraduates by Robert Ash (has full solutions to all problems and is a Dover book!)
Partial Differential Equations
Applied Partial Differential Equations with Fourier Series and Boundary Value Problems by Richard Haberman
Partial Differential Equations for Scientists & Engineers by Stanley Farlow
Fourier Analysis
Fourier Series by Georgi Tolstov
Fourier Analysis: An Introduction by Stein and Shakarchi
Calculus of Variations
Calculus of Variations by Gelfand and Fomin
Calculus of Variations: with Applications to Physics and Engineering by Robert Weinstock
Calculus of Variations by Lev Elsgolc
Numerical Analysis
A First Couse in the Numerical Analysis of Differential Equations by Arieh Iserles (This book was tough for me without the help of my professors lecture notes/explanations. I think it requires a certain level of mathematical maturity.)
Numerical Methods for Engineers by Chapra and Canale (much more approachable than the Iserles book, but it is not written for mathematicians unlike the Iserles book)
Differential Geometry
A Course of Differential Geometry and Topology by A. Mishchenko and A. Fomenko (Mir Publishers Moscow)
Differential Geometry by Erwin Kreyszig
Measure Theory
Okay, while I have not studied measure theory formally, I plan on doing so using the following book(s). I have the hardcover version, but if you can learn from PDFs well enough, then Axler's book is a good option.
Measure, Integration, and Real Analysis by Sheldon Axler (can be found here for free from the author)
Real Analysis by Royden
General Interest
Infinite Powers: How Calculus Reveals the Secrets of the Universe by Steven Strogatz
A Student's Guide to Laplace Transforms by Daniel Fleish
All the Mathematics You Missed: But Need to Know for Graduate School by Thomas Garrity
The Joy of X: A Guided Tour of Math, from One to Infinity by Steven Strogatz
--- Physics and Engineering Books ---
General Physics
Sears and Zemansky's University Physics with Modern Physics by Young and Freedman (I used this to learn physics)
Fundamentals of Physics by Halliday, Resnick, and Walker (I haven't used this, but have heard many good things)
Engineering Statics
Engineering Mechanics: Statics by Russell Hibbeler
Engineering Dynamics
Engineering Mechanics: Dynamics by Russell Hibbeler
Mechanics of Materials
Mechanics of Materials by Russell Hibbeler
Schaum's Outline of Strength of Materials by Merle Potter
Classical Mechanics
I haven't taken a classical mechanics course, but I used Taylor's text on my own to learn Lagrangian mechanics and some stuff about vibrations. I found it to be very easy to read.
Classical Mechanics by John R. Taylor
Introduction to Classical Mechanics by David Morin
Quantum Mechanics
I want to learn quantum mechanics very badly, but have not had the time to dive into it. These are the books I own and plan to use to accomplish that goal. I have seen glowing reviews for these and so I believe in their value.
Introduction to Quantum Mechanics by David Griffiths (a gentler text for undergrads)
Principles of Quantum Mechanics by Shankar (this one looks really good!)
Modern Quantum Mechanics by Sakurai (pretty sure this is more of a grad level book. I don't own this one yet.)
Thermodynamics
Fundamentals of Engineering Thermodynamics by Moran and Shapiro (I read nearly every word of this book and really liked it!)
Fluid Mechanics
Munson, Young, and Okiishi's Fundamentals of Fluid Mechanics by Gerhart, Hochstein, and Gerhart
Schaum's Outline of Fluid Mechanics by Potter and Wiggert
Heat Transfer
Fundamentals of Heat and Mass Transfer by Bergman and Lavine
Nuclear Engineering
These are ones that I have perused a bit, but want to study in detail in the future. So far, I have only made it through Ch. 1 of the first two :/.
Fundamentals of Nuclear Science and Engineering by Schultis and Faw
Nuclear Reactor Engineering: Reactor Design Basics 4ed Vol I by Glasstone and Sesonske
DOE Fundamentals Handbook: Nuclear Physics and Reactor Theory Volume I of II (download this here)
DOE Fundamentals Handbook: Nuclear Physics and Reactor Theory Volume II of II (download this here)
--- Military/National Security ---
Biographies
Marine Sniper: 93 Confirmed Kills by Charles Henderson
War Shots: Norm Hatch and the US Marine Corps Combat Cameramen of World War II by Charles Jones and James Jones (see the footage Norm Hatch captured here on YouTube)
Chemical Weapons
The Chemical Warfare Service: From Laboratory to Field by U.S. Army Center of Military History
General
The Pentagon's Brain: An Uncensored History of DARPA, America's Top Secret Military Research Agency by Annie Jacobsen
The Art of Intelligence: Lessons from a Life in the CIA's Clandestine Service by Henry Crumpton
Memoirs
Skunk Works: A Personal Memoir of My Years at Lockheed by Ben Rich
One Bullet Away: The Making of a Marine Officer by Nathaniel Fick
Shady Lady: Flying the 'Dragon Lady' U-2 Spy Plane by Rick Bishop
The Guerrilla Factory: The Making of Special Forces Officers by Tony Schwalm
Nuclear Weapons
Command and Control: Nuclear Weapons, the Damascus Incident, and the Illusion of Safety by Eric Schlosser
15 Minutes: General Curtis LeMay and the Countdown to Nuclear Annihilation by L. Douglas Keeney
Nuclear Strategy in the Modern Era: Regional Powers and International Conflict by Vipin Narang
The Logic of American Nuclear Strategy: Why Strategic Superiority Matters by Matthew Kroenig
Nuclear War Survival Skills by Cresson H. Kearny (from Oak Ridge Nat'l Laboratory)
Tactical Nuclear Weapons: Emergent Threats in an Evolving Security Environment by Brian Alexander
The Effects of Nuclear Weapons, 3rd Edition by Samuel Glasstone and Philip Dolan [online version here]
Submarines
Blind Man's Bluff: The Untold Story of American Submarine Espionage by Sherry Sontag and Christopher Drew with Annette Lawrence Drew
The Hunt for Red October by Tom Clancy (yeah, I know it's fiction but c'mon, it's a classic for a reason!)
---General Reading---
Russian Literature
Anna Karenina by Leo Tolstoy [currently reading, 12/4/24]