What book/textbook would you recommend for an undergrad looking to expand knowledge of oncology?

I've had a very strong interest in oncology for quite a while now, and I've been working in a research lab studying glioblastoma for two years. I've read some books more oriented for the general population, such as The Emperor of All Maladies and The Immortal Life of Henrietta Lacks, but I'd really like to read something a little more challenging and medically oriented. I have access to a great medical library on campus and I'd love some recommendations on where to go from here. Thanks!