Online resources, affordable textbooks, videos
The Worldwide Center of Mathematics (WCoM) was founded in 2008 by Dr. David B. Massey — a career mathematician and educator of more than 30 years. Its mission: To engage and nurture the local and global mathematics communities. Located in Cambridge, Massachusetts, and focused solely on mathematics, the Center of Math publishes research and other academic resources. Leveraging today’s technology, the Center of Math produces primarily digital resources, including textbooks, videos, research and more.
Learn more at http://centerofmath.org/about/index.html#subject1