Street-Fighting Mathematics
For the people who did not notice, in the "Open Access" tab you can download the PDF of the whole book legally and for free.<p>There is also a second book by the same author which is a bit harder and more comprehensive, and also open access:<p><a href="https://mitpress.mit.edu/books/art-insight-science-and-engineering" rel="nofollow">https://mitpress.mit.edu/books/art-insight-science-and-engin...</a>