>>2498196 lb

'sigle'

https://www.opengrey.eu/

https://www.greynet.org/greysourceindex.html

https://europa.eu/rapid/press-release_MEMO-86-5_en.htm

https://www.computescotland.com/opensigle-the-open-sesame-to-european-grey-literature-1429.php

https://invenio.nusl.cz/record/42004?ln=en

just a few