Hello, I'm a first year graduate student, and one of the required texts for my class is the book alluded to in the title. However, it seems to me that this book is written in the language of a mathematician, and is a bit inaccessible to me. Particularly, I'm having trouble following the proofs. I'm not familiar with proof-writing or the concept of measures, both of which are frequently used. Could anyone advise a reference for someone who has had basic undergraduate math for physics majors (PDEs, Complex variables, Linear Algebra, etc.), and taken a basic graduate-level math methods course, but is unfamiliar with the abstract mathematics in this book that might be able to get me up to speed, at least well enough to follow this book? Thanks.