Valentini, G., Iudici, M., Walker, U. A., Jaeger, V. K., Baron, M., Carreira, P., Czirják, L., Denton, C. P., Distler, O., Hachulla, E., Herrick, A. L., Kowal-Bielecka, O., Pope, J., Müller-Ladner, U., Riemekasten, G., Avouac, J., Frerix, M., Jordan, S., Minier, T., Siegert, E., Ong, V. H., Vettori, S., & Allanore, Y. (2017). the European Scleroderma Trials and Research group (EUSTAR) task force for the development of revised activity criteria for systemic sclerosis: derivation and validation of a preliminarily revised EUSTAR activity index. Annals of the rheumatic diseases, 76(1), 270–276. http://access.bl.uk/ark:/81055/vdc_100135179084.0x00005d