MathDL 
Mathematical Association of America’s Mathematical Sciences Digital Library

Mathematics on the Web 
American Mathematical Society (AMS)

ViFaMATH 
Virtuelle Fachbibliothek Mathematik  - SUB Göttingen

Digitization Registry 
SUB Göttingen. The Digitisation Registry provides information about digitisation projects and access to digitized materials.

The Electronic Library of Mathematics 
EMS; free online journals, article collections, and monographs in the field of mathematics

European Mathematical Information Service EMIS 
European Mathematical Society (EMS) - u.a. Testzugänge zu MATH (Zentralblatt) und MATHDI

MAA Podcast Center
Mathematical Association of America

MacTutor History of Mathematics archive 
University of St Andrews, Scotland - a integrated collection of over 1000 biographies and historical articles

The Mathematical Atlas 
a collection of articles about aspects of mathematics at and above the university level, Dave Rusin

Mathematical functions 
über 37000 mathematische Formeln und Funktionen

Mathematics Books Online 
AMS, frei zugängliche Online-Mathematikbücher

Metamaths 
Norman Megill (MIT), maschinelle Verifikation von Beweisen

swiss electronic academic library service 
Commentarii Mathematici Helvetici 1929-1996, L'Enseignement Mathématique 1899-2000