Please note that these resources have been opened (with some limitations) temporarily by the vendors and publishers in order to help reduce the impact COVID-19 has on academic communities and access to information at and through Libraries. Continued and on-going access may not be guaranteed, and you may eventually lose access or hit a paywall (What is a paywall?).
OCLC is maintaining a growing list of freely available content, which includes recommended options to access sources through OCLC services. Downloadable spreadsheet which is updated regularly.