Hello! I am currently using Apostol's Calculus volume 1 book, and going to take multivariable calculus-linear algebra-differential equations course on Fall semester that uses the volume 2 book of Apostol. Although the Apostol book is very outstanding, I feel like some of the topics are very difficult to understand and book does not have many problems. I did some search, and I found the schaum's outlines for calculus, advanced calculus, 3000 calculus problems, linear algebra, differential equations, and ordinary DE. Are those books good for supplements? Do you think they will go perfectly with Apostol's volume 1 and 2 books?