According to Aleph 0’s guide video:

REAL ANALYSIS Book: “Understanding Analysis” by Stephen Abbott. Videos: Lectures by Francis Su (https://www.youtube.com/playlist?list…)

LINEAR ALGEBRA Book: “Linear Algebra Done Right” by Sheldon Axler Videos: Sheldon Axler’s Playlist (https://www.youtube.com/playlist?list…)

POINT SET TOPOLOGY Online Notes with Problems: MAT327 Course Notes (http://www.math.toronto.edu/ivan/mat3…)

COMPLEX ANALYSIS Intro Book: “Visual Complex Functions: an Introduction with Phase Portraits” by Elias Wegert More Technical Book: “Complex Analysis” by Serge Lang Videos: Wesleyan University Playlist (https://www.youtube.com/playlist?list…)

GROUP THEORY Book: “Topics in Algebra” by Herstein (Chapter 2) Videos: Lectures by Benedict Gross (https://www.youtube.com/playlist?list…)

GALOIS THEORY Notes by Tom Leinster: https://www.maths.ed.ac.uk/~tl/gt/gt.pdf

DIFFERENTIAL GEOMETRY Book: Introduction to Differentiable Manifolds and Riemannian Geometry by Boothby

ALGEBRAIC TOPOLOGY Book: Algebraic Topology by Allen Hatcher (available for free on his website: https://pi.math.cornell.edu/~hatcher/…) Videos: Lectures by Pierre Albin (https://www.youtube.com/playlist?list…)