Data from published papers:

LOFAR LBA Sky Survey (de Gasperin+ A&A, 648, A104):
Data: https://www.lofar-surveys.org/lba.html

Diffuse Radio Emission from Galaxy Clusters (van Weeren, de Gasperin+ Space Science Reviews, 215, id.16)
Data: http://www.galaxyclusters.com

A radio spectral index map and catalogue at 147–1400 MHz covering 80 per cent of the sky (de Gasperin+ MNRAS 474, 5008)
Data: http://tgssadr.strw.leidenuniv.nl/spidx