* Basic Mathematics by Serge Lang
* Calculus Made Easy by Silvanus Thompson
Then try a DIY bootcamp in the spirit of Harvard Math 55. If you are interested in continuous math:
* Vector Calculus by Hubbard & Hubbard
If you are interested in discrete mathematics and computation:
* Logic in Computer Science by Huth & Ryan
* Basic Mathematics by Serge Lang
* Calculus Made Easy by Silvanus Thompson
Then try a DIY bootcamp in the spirit of Harvard Math 55. If you are interested in continuous math:
* Vector Calculus by Hubbard & Hubbard
If you are interested in discrete mathematics and computation:
* Logic in Computer Science by Huth & Ryan