Computers and Electronics
Foreign Language
  Geometry and Trigonometry
  Differential Equations
  Linear Algebra
  Proofs and Logic
  Advanced Topics



Pre-algebra (OpenStax)  textbook 
"Introduces the fundamental concepts of algebra while addressing the needs of students with diverse backgrounds and learning styles."
Beginning and Intermediate Algebra  textbook 
A standard introduction to algebra, beginning with a review of pre-algebra.
College Algebra (OpenStax)  textbook 
"A comprehensive exploration of algebraic principles; meets scope and sequence requirements for a typical introductory algebra course."

Geometry and Trigonometry

Dave's Short Trig Course
An introduction to trigonometry that assumes knowledge of algebra and geometry.
Trigonometry  textbook 
"A text on elementary trigonometry, designed for students who have completed courses in high-school algebra and geometry."
Euclid's Elements Redux  textbook 
"An open textbook on mathematical logic and geometry based on Euclid's 'Elements'."
Euclidean plane and its relatives  open-source  textbook 
"Designed for a semester-long course in Foundations of Geometry and meant to be rigorous, conservative, elementary and minimalist."


Precalculus  open-source  textbook 
"Presented at a level that definitely prepares a student for Calculus while giving them relevant Mathematics which can be used in other classes as well."
mooculus  textbook 
"A first and friendly introduction to calculus, suitable for someone who has never seen the subject before, or for someone who has seen some calculus but wants to review the concepts and practice applying those concepts to solve problems."
Fundamentals of Calculus  textbook  open-source 
"Covers the first semester of a freshman calculus course."
Yet Another Calculus Textbook  textbook 
"An introduction to calculus based on the hyperreal number system. Although the book does not explicitly assume any prerequisites beyond basic algebra and trigonometry, in practice the pace is too fast for most of those without some acquaintance with the basic notions of calculus."

Differential Equations

Diffy Qs: Differential Equations for Engineers  open-source  textbook 
"A one-semester first course on differential equations, aimed at engineering students. Prerequisite for the course is the basic calculus sequence."

Linear Algebra

Linear Algebra Done Wrong  textbook 
"A first linear algebra course for mathematically advanced students. It is intended for a student who, while not yet very familiar with abstract reasoning, is willing to study more rigorous mathematics than is presented in a 'cookbook style' calculus type course."
Elements of Abstract and Linear Algebra  textbook 
"A survey of abstract algebra with emphasis on linear algebra. It is intended for students in mathematics, computer science, and the physical sciences."

Proofs and Logic

A Gentle Introduction to the Art of Mathematics  textbook  open-source 
"Covers several topics in the foundations of mathematics (logic, sets, relations, functions and cardinality) and introduces the reader to many techniques of mathematical proof (direct, indirect, contradiction, contrapositive, mathematical induction, combinatorial proofs and magic)."
Book of Proof  textbook 
"Learn and apply the methods of thought that mathematicians use to verify theorems, explore mathematical truth and create new mathematical theories."

Advanced Topics

An Infinitely Large Napkin  textbook 
A broad survey of higher mathematics.