1. Bubel A (1976) Electron microscope studies on the operculum of Spirorbis spirorbis (L.). In: Sharpley JM, Kaplan AM (eds) Proceedings of the international biodegradation symposium no. 3. Applied Science Publishers, London, pp 495–514
2. Bubel A (1983) A fine structural study of the calcareous opercular plate and associated cells in a polychaete annelid. Tissue Cell 15:457–476
3. Bubel A, Thorp CH, Fitzsimmons CAL (1977) An histological and electron microscopical study of opercular regeneration in the serpulid, Pileolaria (P.) granulata, with particular reference to the formation of the calcareous opercular plate. In: Romanovsky V (ed) Proceedings of the 4th international congress on marine corrosion and fouling, Juan-les-Pins, Antibes, pp 85–96
4. Bubel A, Thorp CH, Moore MN (1980) An histological, histochemical and ultrastructural study of the operculum of the serpulid Pomatoceros triqueter L. with particular reference to the formation of the calcareous opercular plate during opercular regeneration. In: Oxley TA, Allsopp DA, Becker G (eds) Proceedings of the international biodegradation symposium no. 4, pp 275–290
5. Bubel A, Thorp CH, Fenn RH, Livingstone D (1985) Opercular regeneration in Pomatoceros lamarckii Quatrefages (Polychaeta: Serpulidae). Differentation of the operculum and deposition of the calcareous opercular plate. J Zool Lond Ser B 1:49–94