Textbooks in Mathematics
at 110mb

• Notes on Diffy Qs: Differential Equations for Engineers by Jiří Lebl
  
• Proofs and Concepts by Dave Witte Morris, and Joy Morris
  
• Introduction to Real Analysis by William F. Trench
  
• Vector Calculus by Michael Corral
  
• Understanding Calculus by Faraz Hussain
  
• A ProblemText in Advanced Calculus by John M. Erdman
  

A<B notes for the Math Olympiad Program by Kiran S. Kedlaya

elementary mathematics, Analysis,Lebesgue Integrals ..

• Basic Concepts of Mathematics by Elias Zakon
  
• Mathematical Analysis I by Elias Zakon
  
• Calculus by Gilbert Strang
  
• MEASURE THEORY Vol1 by David H. Fremlin
  
• MEASURE THEORY Vol2 by David H. Fremlin
  
• MEASURE THEORY Vol3 by David H. Fremlin
  
• MEASURE THEORY Vol4 by David H. Fremlin
  
• Real Analysis for Engineers by Erhan Cinlar, and Robert J. Vanderbei
  
• Measure Theory and Integration by Vitali Liskevich
  
• The Matrix Cookbook by Kaare Brandt Petersen
  
• Classical Geometry and Low-Dimensional Topology by Danny Calegari
  
• Basic algebra and trigonometry by Thomas Ward
  
• First Year Mathematics by William Chen
  
• Multivariable Calculus by George Cain, and James Herod
  
• Complex Analysis by George Cain
  
• Linear Algebra by Jim Hefferon
  
• Elementary Linear Algebra by Keith Matthews
  
• A First Course in Linear Algebra by Robert A. Beezer
  
• Complex Analysis by Douglas N. Arnold
  
• Set Theoretic Real Analysis by Krzysztof Ciesielski
  
• Expository notes in The finite reflection groups by Daniel Allcock
  
• Classical Geometry by Danny Calegari
  
• Difference Equations to Differential Equations by Dan Sloughter
  
• Course of linear algebra and multidimensional geometry by Ruslan Sharipov
  
• Examples, Lecture Notes and Specimen Exam Questions and Natural Sciences Tripos
  
• Calculus project by Michael Livshits
  
• The Octonions by John C. Baez
  
• Advanced Calculus by Shlomo Sternberg
  

Mathematical Logic and Set theory

• Mathematical Logic - an Introduction by Michal Walicki
  
• Set theory by Peter G. Dixon
  
• Mathematical Logic by Stephen G. Simpson
  
• Foundations of Mathematics by Stephen G. Simpson
  
• Model Theory by Stephen G. Simpson
  
• A Problem Course in Mathematical Logic by Stefan Bilaniuk
  
• Computability and Incompleteness by Jeremy Avigad
  
• Complete proofs of Gödel's Incompleteness Theorems by Byunghan Kim
  
• Fundamentals of Model Theory by William Weiss, and Cherie D'Mello
  
• Logic for Everyone by Robert A. Herrmann
  

Discrete Math

• Lecture Notes on Discrete Mathematics by László Lovász
  

Whitman Calculus by David Guichard

Olympiad Inequalities by Thomas J. Mildorf

Elementary Real Analysis by Andrew M. Bruckner, Brian S. Thomson, and Judith B. Bruckner

Precalculus (Electronic version annually updated.) by David H. Collingwood, and K. David Prince

Introductory Number Theory

p-adic numbers

Arithmetic Geometry

Fermat's Last Theorem

Algebraic Number Theory

Analytic Number Theory

Algebra, Abstract

Algebraic Geometry

Elliptic Curves

Category Theory

Lie Algebras

• Textbook in Problems on Elementary Topology by O.Ya.Viro, O.A.Ivanov, V.M.Kharlamov, and N.Y.Netsvetaev
  
• Topology Course by Aisling McCluskey, and Brian McMaster
  
• Topology by Thomas Ward
  
• Foliations and the topology of 3-manifolds by Danny Calegari
  

Algebraic Topology

K-Theory

Knots

• Homeomorphisms in Analysis by Casper Goffman, Togo Nishiura, and Daniel Waterman
  
• Why the Boundary of a Round Drop Becomes a Curve of Order Four by A. N. Varchenko, and P. I. Etingof
  
• Lectures on Entire Functions by B. Ya. Levin
  
• Constructive Real Numbers and Constructive Function Spaces by N. A. Sanin
  
• Complex Variables by W.P. Novinger, and Robert B. Ash
  
• Foundations of Nonstandard Analysis by Erland Gadde
  
• Analytic functions by Stanislaw Saks, and Antoni Zygmund
  
• Theory of Functions of real variable by Shlomo Sternberg
  

Functional Analysis

Differential Equations

Differential Geometry

Dynamics

Entropy

Quantum Mechanics

Quantum Field Theory

Condensed Matter

Photonic Crystals: Molding the Flow of Light by John D. Joannopoulos, Steven G. Johnson, Joshua N. Winn, and Robert D. Meade

Special and General Relativity

• General Relativity, Nonlinear PDEs, etc by Sergiu Klainerman
  
• Special Relativity and Geometry by C. E. Harle, and R. Bianconi
  
• Differential Geometry (and Relativity) by Bob Gardner
  
• General Relativity and Quantum Cosmology by Sean M. Carroll
  
• Public lectures by Stephen Hawking and Roger Penrose
  

Physics

• Essential Physics 1 by Frank Firk
  
• Introduction to Groups, Invariants & Particles by Frank W.K. Firk
  
• Classical Electrodynamics by Bo Thidé
  
• Classical electrodynamics and theory of relativity by Ruslan Sharipov
  
• Electromagnetic Theory and Computation: A Topological Approach by Paul W. Gross, and P. Robert Kotiuga
  
• MOTION MOUNTAIN TEXTBOOK Hiking beyond space and time along the concepts of modern physics by Christoph Schiller
  
• Fundamentals of Thermodynamics by J. Karl Johnson
  
• Non-Equilibrium Statistical Mechanics by Klaus Schulten
  
• Course in Electrodynamics by Franz Wegner
  
• Light and Matter by Ben Crowell
  
• Order-of-magnitude-physics by Sanjoy Mahajan
  
• Physical Applications of Geometric Algebra by Anthony Lasenby, and Chris Doran
  
• Group Theory: Lie's, Tracks, And Exceptional Groups by Predrag Cvitanovic'
  
• An Elementary Introduction to Groups and Representations by Brian C. Hall
  
• Geometric Models for Noncommutative Algebras by A. Cannas da Silva, and A. Weinstein
  
• Differential Forms in Electromagnetic Theory by Richard H. Selfridge, David V. Arnold, and Karl F. Warnick
  
• Lectures on integration of several variables by Michael Adler
  
• Methods of Mathematical Physics by Mark Trodden
  
• Further Mathematical Methods by Niels Walet
  
• Computational Physics by Angus MacKinnon
  
• Zeno meets modern science by Zurab K. Silagadze
  
• Feynman's derivation of Maxwell equations and extra dimensions by Zurab K. Silagadze
  
• TeV scale gravity, mirror universe, and ... dinosaurs by Zurab K. Silagadze
  
• Quick introduction to tensor analysis by Ruslan Sharipov
  
• Traveling Wave Solutions of Parabolic Systems by Aizik I. Volpert, Vitaly A. Volpert, and Vladimir A. Volpert
  

• Introduction to Probability by Charles Grinstead, and J. Laurie Snell
  
• Probability Tutorials by Noel Vaillant
  
• Probability Theory: The Logic of Science by Edwin Thompson Jaynes
  
• Probability Theory As Extended Logic by Larry Bretthorst
  
• Introduction to Probability by Oliver Knill
  
• Random Walks and Diffusion by Martin Z. Bazant
  
• Reversible Markov Chains and Random Walks on Graphs by David Aldous, and Jim Fill
  
• An Invitation to Sample Paths of Brownian Motion by Yuval Peres
  
• Notes on probability theory by Hendrik W. Lenstra, Jr.
  
• An introduction to stochastic differential equations by Lawrence Craig Evans
  
• Stochastic Calculus by Alan Bain
  
• Probability Theory by S.R.S.Varadhan
  
• Statistics by S.R.S.Varadhan
  
• Stochastic Processes by S.R.S.Varadhan
  
• Stochastic Differential Equations by Thomas G. Kurtz
  
• Stochastic Integration and Stochastic Differential Equations by Klaus Bichteler
  
• Probability, Random Processes, and Ergodic Properties by Robert M. Gray
  

• Derivations of Applied Mathematics by Thaddeus H. Black
  
• Linear Methods of Applied Mathematics by Evans Harrell, and James Herod
  
• Linear Algebra, Infinite Dimensions, and Maple by James Herod
  
• generatingfunctionology by Herbert Wilf
  
• Algorithms and Complexity by Herbert S. Wilf
  
• A=B by Herbert Wilf, Marko Petkovsek, and Doron Zeilberger
  
• Applied Math Textbook by Sean Mauch
  
• Mathematical Tools for Physics by James Nearing
  
• Applied Mathematics by Peter J. Olver, and Chehrzad Shakiban
  
• Surveys in Combinatorics
  
• Computational Complexity: A Conceptual Perspective by Oded Goldreich
  
• Papers on Combinatorial Enumeration and Asymptotics by Andrew Odlyzko
  
• Hyperplane Arrangements by Richard Stanley
  
• Introduction to Statistical Signal Processing by R.M. Gray, and L.D. Davisson
  
• Applied Abstract Algebra by David Joyner, Richard Kreminski, and Joann Turisco
  

Numerical Analysis

Information Theory

Financial mathematics

Game Theory

Cryptography

• Mathematics under the Microscope by Alexandre Borovik
  
• What is and what will be: Integrating spirituality and science by Paul Budnik
  

Fractals

Graph Theory

Coxeter groups

Nielsen Fixed Point Theory

Permutation Puzzles