I'm not teaching a co-class for MAT21A this quarter, but these are notes from the last time that I did.
Kouba's MAT21A Site
Grant's MAT21A Site
I'm not teaching a co-class for MAT21B this quarter, but here are resources from the last time I did.
Kouba's MAT21B Site
Grant's MAT21B Site
These are mostly notes for topics in Chapter 16 - all the fun theorems!