1. : Textbook of the Rheumatic Diseases (ed. 3.). Edinburgh and London, E. & S. Livingstone Ltd., 1964, p. 571.
2. : Pathology of the Connective Tissue Diseases. London, Edward Arnold Publishers Ltd., 1965, p. 409.
3. : Textbook of Pathology (ed. 2). Philadelphia and London, W. B. Saunders Co., 1962, p. 1097.