The University of Michigan has one of the best libraries in the world. We also have a dedicated math (and stats) librarian, Samuel Hansen, who has a MS degree in mathematics and is a gifted communicator of math. Among other projects, they are the host of the popular mathematics podcast Relatively Prime.
Samuel has put together a research guide for mathematicians at UM, with links to all the major sources and arxivs. Look for them in Junior Colloquium next year!