Della Rossa, A., Valentini, G., Bombardieri, S., Bencivelli, W., Silman, A. J., D'Angelo, S., Cerinic, M. M., Belch, J. F., Black, C. M., Becvar, R., Bruhlman, P., Cozzi, F., Czirják, L., Drosos, A. A., Dziankowska, B., Ferri, C., Gabrielli, A., Giacomelli, R., Hayem, G., Inanc, M., McHugh, N. J., Nielsen, H., Scorza, R., Tirri, E., van den Hoogen, F. H. J., & Vlachoyiannopoulos, P. G. (2001). european multicentre study to define disease activity criteria for systemic sclerosis. I. Clinical and epidemiological features of 290 patients from 19 centres. Annals of the rheumatic diseases, 60(6), 585–591. http://access.bl.uk/ark:/81055/vdc_100130162966.0x00005a