Salman Khan began making math videos for his cousin in 2004. He posted them on YouTube and they have become a mainstay for anyone looking for math videos.

MIT OpenCourseWare is a great site with videos and PDFs on a wide range of subjects. The Mathematics Department has several courses on Calculus. 

Paul Dawkins is a Lamar University professor who has published his class notes online. Sadly, the site looks like it was created in the '90s and has never been updated. Fortunately, the class notes do a great job of explaining things and working out problems in detail. 

OpenStax is part of Rice University, which is a nonprofit charitable corporation. Openstax publish high-quality, peer-reviewed, openly licensed college textbooks that are absolutely free online and low cost in print.

Barron’s provide books from general learning and pre-college test prep to professional certification and upskillinghas. Written by experienced educators and professionals, our trusted resources are ideal for use both in and out of the classroom. 

The Larson Calculus series, authored primarily by Ron Larson, is a widely used set of textbooks for calculus courses, often adopted in high school and college-level mathematics courses. 

5 Steps to a 5 guides are robust in-class tools that contain concise topic reviews, plenty of test prep, and subject-specific resources for AP teachers pressed for time! 5 Steps to a 5 provides support to reinforce the retention of concepts and skills covered in their AP course.