MathSciNet, the
on-line version of Mathematical Reviews
(Full access, but only from subscribing sites, such as Dalhousie)
MATH Database, the
online version of Zentralblatt für Mathematik
(full access only from subscribing sites; limited access elsewhere, including Dalhousie)
Electronic Research
Archive for Mathematics, the online version of the Jahrbuch über
die Fortschritte der Mathematik (1868-1943), the prototype of all
reviewing journals. Free access.