"Calculus," a book written by Gilbert Strang and used in his courses at MIT, is available online at MIT.edu in addition to a teacher's manual and study guide for students. OpenStax College, a nonprofit initiated by Rice University, offer a free book titled "Introductory Statistics" on OpenStaxCollege.org.
Stang's calculus textbook covers both single-variable and multivariable calculus, making it a comprehensive sources for typical high school and college calculus courses. The book contains real-world examples and is promoted as a good resource for self-learners. OpenStax's statistics book is part of a suite of books the online resource offers; other books students can download include algebra and trigonomety texts and a precalculus textbook.