online digital math libraries and Physics libraries

Mathematics

There are multiple formal math databases:

• Mizar
• Metamath

In addition to formal math databases, there are digital math libraries

• Digital Math Library; https://www.math.uni-bielefeld.de/~rehmann/DML/dml_links.html
• the proposed "World Digital Mathematics Library (WDML)" was rebranded to the "Global Digital Mathematics Library" run by the International Mathematical Knowledge Trust's GDML working group.
• AMS Digital Mathematics Registry
• European Digital Mathematics Library (EuDML)
• arxiv

These digital math libraries are relevant for searching and parsing content.


"How to Build a Global Digital Mathematics Library" by S Watt
https://cs.uwaterloo.ca/~smwatt/pub/reprints/2016-synasc-gdml.pdf

Physics

• https://inspirehep.net/; https://en.wikipedia.org/wiki/INSPIRE-HEP
• https://arxiv.org/archive/physics
• http://network.bepress.com/physical-sciences-and-mathematics/physics/
• astrophysics data system
• NIST reference data for Physics; constants

See also 

https://guides.lib.unc.edu/az.php?s=1185

https://physicalsciences.library.cornell.edu/physics-databases/

Teaching resource: https://www.compadre.org/