1. Alexander, W. R. M., Bremner, Joan M., and Duthie, J. J. R. (1960). Ann. rheum. Dis., 19, 338.
2. In "The Epidemiology of Chronic Rheumatism";Graaff, R.de; Laine, V.; Lawrence, J.S.,1963
3. Gratama, S. (1957). Docum. Med. geogr. trop. (Amst.), 9, 237.
4. In "The Epidemiology of Chronic Rheumatism";Hijmans, W.,1963
5. The Epidemiology of Chronic Rheumatism;Kellgren, J.H.,1963