The main text for the course is:
B. Simon, Operator Theory: A Comprehensive Course in Analysis, Part 4, AMS (2015) (Online through MSU Library)
Additional topics may be taken from the following texts, all of which are quite useful references:
O. Bratelli and D. Robinson, Operator Algebras and Quantum Statistical Mechanics 1, Springer (1987) (Online through MSU Library)
T. Kato, Perturbation Theory for Linear Operators, Springer (1995) (Online through MSU Library)