Cornell University hosts this impressive collection of Historical Math Monographs, made available for free public viewing online. The default option for reading the books is to view pages as images within a Web browser, but users can also choose to view text only; another option is to view pages as pdf files (but this may not be working properly). Many authors have works showcased in the collection, including Descartes, Neumann, and others. The documents are only presented in their original language, and hence there are German, French, and English works.