1. Åkesson, B., 1958: A study of the nervous systems of the Sipunculoidae, Undersökn. Öresund 38:1–249.
2. Akesson, B., 1961, Some observations on Pelagosphaera larvae, Galathea-Rep. 5:7–17.
3. Akesson, B., 1963, The comparative morphology and embryology of the head in scale worms (Aphroditidae, Polychaeta), Arkiv Zool. 16(7):125–163.
4. Barber, V. C, and Wright, D., 1969, The fine structure of the eye and optic tentacles of the mollusc Cardium edule.J. Ultrastruct. Res. 26(5–6):515–528.
5. Barber, V. C, Evans, E., and Land, E., 1967, The fine structure of the eye of the mollusc Pecten maximus, Z. Zelljorsch. Mikrosk. Anat. 76:295–312.