1. Black C. The aetiopathogenesis of systemic sclerosis: Thick skin–thin hypotheses. J R Coll Physicians1995; 29:119–28.
2. Harkness RD. Mechanical properties of collagenous tissues. In: Gould BS, ed. Treatise on collagen, Vol. 2A. New York. Academic Press, 1968;247–310.
3. Wigley FM. Clinical features of systemic sclerosis. In: Klippel JH, Dieppe PA, eds. Rheumatology, edn 2. London: Mosby, 1998, Chapter 7.9.
4. Brennan P, Silman A, Black C, Bernstein R, Coppock J, Maddison P. Reliability of skin involvement measures in scleroderma. Br J Rheumatol1992;31:457–60.
5. Black C. Measurement of skin involvement in scleroderma. J Rheumatol1995;22:1217–9.