Heald, G. H., Pizzo, R. F., Orrú, E., Breton, R. P., Carbone, D., Ferrari, C., et al. (2015). The LOFAR Multifrequency Snapshot Sky Survey (MSSS) - I. Survey description and first results. Astronomy & Astrophysics, 582: A123, pp. 1-22. doi:10.1051/0004-6361/201425210.