arXiv is a preprint repository in physics, math, computer science and related disciplines enabling scientists worldwide to share and access research before it is formally published.
The original articles are from the online Encyclopaedia of Mathematics, published by Kluwer Academic Publishers in 2002; graduate-level reference work.
the web's most extensive mathematical resource, assembled over more than a decade by Eric W. Weisstein with assistance from thousands of contributors; updated daily.
zbMATH Open (formerly known as Zentralblatt MATH) is the abstracting and reviewing service in pure and applied mathematics drawn from more than 3,000 journals and book series, and some 190,000 books. It is edited by the European Mathematical Society (EMS), the Heidelberg Academy of Sciences and Humanities, and FIZ Karlsruhe.
