For self-studying calculus, recommended texts include Michael Spivak's 4th Edition, Tom Apostol's 1st and 2nd Editions, and Richard Courant's introductory calculus/analysis books. Walter Rudin's Mathematical Analysis is suggested as a follow-up, but it's noted that starting with Rudin may be challenging without prior calculus knowledge. A solid understanding of proofs is emphasized as crucial for tackling Apostol effectively. Additionally, "How to Prove It" by Daniel J. Velleman and "How to Solve It" by George Polya are recommended for developing proof skills. These resources collectively provide a rigorous foundation for advancing in calculus and mathematical analysis.