Medical school books

Hello! My name is Alfonso Vivanco, I am a medical (and mathematics) school student from Mexico currently during my fourth year studying, and due to the fact of both majors, it is hard for me to have a side-job during my studies (alothough I tried it a few times!), and I want to fully commit with my studies, and learn the most I can during these years, and to be able to, in the future, to save lives both through medicine and mathematics (modeling diseases, biochemical reactions, and so forth) working at Doctors without borders or at the WHO; it is because of this, that I kindly ask you to help me with a fund for my books for the next semester: hematology, rheumatology, internal medicine.

Thanks a lot!!!