American River Software
Mathematics
Calculus with Analytic Geometry
This is an excellent introductory undergraduate text. It contains proofs to many theorems not found in other introductory texts. It is currently out of print (copyright 1965). Solutions to selected exercises from all chapters (1 through 22) are available for download.
Elementary Number Theory
This is an excellent introductory undergraduate text. Solutions to all the exercises from chapters 1 through 9 (The Quadratic Reciprocity Law) of the 5th edition are available for download.
Introduction
to Linear Algebra
This is an undergraduate introductory text. Solutions to selected exercises of the 3rd edition from chapters 1-7 are available for download.
Vector Calculus
This is an undergraduate text. Although explanations of some topics may be better and more thorough in other undergraduate texts, the exercises from this book are a bit more challenging, and solutions to virtually all the exercises in the 6th edition are available for download.