Springer has dozens of book series in mathematics, they allow downloads of chapter or whole books
Access to electronic editions of journals and electronic books to which Penn State University Libraries subscribes, published by a company called Springer-Verlag. Journals cover the fields of chemistry, computer science, economics, engineering, environmental sciences, geosciences, life sciences, mathematics, medicine, and physics. Coverage: 1996-present. Updates: Continuous
has many older mathematics books out of copyright, and some Penn State books accessible to us
Sponsored by the libraries of the Committee on Institutional Cooperation, the University of California, and other partners, HathiTrust is a repository of digitized materials in all disciplines. Its content--primarily scanned books and journals-- may be searched via authors, titles, subjects, and other data elements.