Project Euclid hosts digital copies of mathematics and theoretical physics journals and conference proceedings.
Physics news and current events coverage from the Institute of Physics.
Repository of research papers and scientific data from institutions worldwide.
Publisher of peer-reviewed mathematics and physics journals.
Premier science journal publishing original research papers; requires subscription or institutional access.
Living Reviews publishes peer-reviewed survey articles on modern physics topics.
Royal Society Publishing distributes peer-reviewed scientific journals.
Hindawi publishes peer-reviewed open-access journals across science and engineering.
European Physical Society publisher; primarily a journal archive, not a teaching or problem-solving resource.
SSRN preprint and working paper repository for economics, finance, and social sciences research.
SDSS provides spectroscopic and imaging data from a large-scale sky survey, used primarily by researchers rather than students solving problems.
A wiki cataloguing unsolved research problems in mathematics and computer science, not exercise material.
Personal website of a mathematician with research materials.
Kvant is a Russian journal for school and undergraduate students in physics and mathematics founded in 1970, with an archive of articles available online.
Portal to Russian mathematics journals; archive for published research rather than study materials.
Uspekhi Fizicheskikh Nauk is a peer-reviewed physics journal; an archive for research papers, not a teaching resource.
Index of Russian-language scientific publications across disciplines.
A French open-access repository for research papers and preprints across disciplines.
A repository of German digitized academic journals from the 19th and 20th centuries.
These are filed under other headings but serve this one too.