Mathematics
Websites
Books
50 Maths Ideas You Really Need to Know by Tony Crilly (2007)
Bridging the Gap to University Mathematics by Edward Hurst and Martin Gould (2009)
The Concise Oxford Dictionary of Mathematics by James Nicholson. 5th edn. (2014)
Foundation Maths by Anthony Croft and Robert Davison. 7th ed. (2020)
How to Study for a Mathematics Degree by Lara Alcock (2012)
How to Think Like a Mathematician by Kevin Houston (2009)
Mathematics - A Basic Introduction by Alan Graham (2013)