Recommendations for modern calculus books include "Calculus: Early Transcendentals" by James Stewart and "Calculus" by Michael Spivak, noted for their clarity and rigor. For modern mathematics, "The Art of Mathematics: Coffee Time in Memphis" by Béla Bollobás is suggested for its engaging approach. Participants emphasize the importance of selecting books that balance theory and application to enhance understanding. The discussion also points to additional resources in the forum's dedicated books section and the "Who Wants to Be a Mathematician" thread for further exploration. Overall, the community encourages exploring a variety of texts to find the best fit for individual learning styles.