1. Rodnan, G.P. Progressive sclerosis (scleroderma). In: Arthritis and Allied Conditions, 9th ed., Editor: McCarthy D.J. Jr., Philadelphia, Lea and Febiger, 1979, 762–809.
2. Le Roy, E.C. Scleroderma (systemic sclerosis). In: Textbook of Rheumatology, Editor: Kelley, W.N., Harris, E.D. Jr., Ruddy, S., Sledge C.B., Philadelphia, Saunders, 1981, 1211–1230.
3. Sharp, G.C., Irwin, W.S., Tan, E.J. et al. Mixed connective tissue disease — an apparently distinct rheumatic disease syndrome associated with a specific antibody to an extractable nuclear antigen (ENA). Am J Med 1972, 52, 145–159.
4. Cohen, M.J., Persellin, R.H. Coexistence of rheumatoid arthritis and systemic sclerosis in four patients. Scand J Rheumatol 1982, 11, 241–245.
5. Mielants, H., Veys, E.M., Verbruggen, G. et al. Intrications of connective tissue diseases. Acta Rhum Belg 1978, 2, 141–162.