I highly recommend the online book "Calculus at Moravian University", it does a pretty good job in building a fundamental understanding of calculus from the bas

I highly recommend the online book "Calculus at Moravian University", it does a pretty good job in building a fundamental understanding of calculus from the basics to multiple integration and vector calculus. I also used Joplin to take notes while reading, it's a notebook app where you can also use LateX (admittedly, many people won't like reading and taking notes on the phone, but I like it since it gives me a chance to learn even when you can't easily use books and laptop) https://webwork.moravian.edu/apexcalc/book-1.html https://webwork.moravian.edu/apexcalc/book-1.html