1. Atheston, L.: The epidermis of Tubifex rivulorum Lamark, with especial reference to its nervous structures. Anat. Anz. 16, 497?509 (1899).
2. Bochenek, A.: L'anatomie fine de la cellule nerveuse d'Helix pomatia. C. R. Ass. des Anat. 5. session. Lyon 1901.
3. Brandenburg, J.: Neurosekretorische Zellen des Regenwurmes. Naturwissenschaften 43, 453 (1956).
4. Clark, R.: On the origin of neurosecretory cells. Ann. Sci. natur. Zool. Ser. 18, 11, 199?207 (1956a).
5. Clark, R.: On the transformation of neurosecretory cells into ordinary cells. Kgl. fysiogr. S�llsk. Lund F�rh. 26, 1?8 (1956b).