This might be of interest to people looking for math textbook suggestions. The Mathematical Association of America maintains a list of books it recommends for acquisition by undergraduate libraries and ranks them from zero stars (suggested for consideration) to three stars (considered essential). You can search the list here:
https://www.maa.org/press/maa-reviews/browse
And you can read more about the list here:
MAA Recommendations for Undergraduate Libraries
This site was mentioned on chat, and the math resources they list look interesting and useful. I think all are free textbooks or lecture notes. I haven’t read through any of them yet, but I know the author of the single variable calculus text (I took a Pascal class from him, haha).
I’ll add a second plug for that calculus text. I’ve always thought calculus texts have become way too bloated, but this one is half the usual length. And reading through the table of contents, I’d say he’s done a great job of deciding which topics to include. Very nice looking.
This is an interesting post that appeared on Hacker News recently, in which a self-learner describes his path of study through what would amount to a very substantial undergraduate math major (probably bleeding over into some graduate study).
Mathematics for the adventurous self-learner
https://www.neilwithdata.com/mathematics-self-learner
Equally interesting was the resulting discussion on HN, much of which was concerned with the question of what to study to prepare for this, namely learning math starting wite pre-algebra. The resources for this that received multiple recommendations were:
(1) Khan Academy
(2) The Demystified series of books by McGraw-Hill
(3) The freely available and peer reviewed books at OpenStax
(4) Your local community college.
My only experience with these is (4), which was my place of employment prior to becoming a stay-at-home dad. In my opinion, that resource does give a pretty good bang for the buck, but admittedly instructor quality can have a fairly high variance.