1. J.J. Wolken, Light Detectors, Photoreceptors, and Imaging Systems in Nature, Oxford University Press, Oxford, 1995.
2. Vision in microalgae;Hegemann;Planta,1997
3. T.H. Bullock, G.A. Horridge, Structure and Function in the Nervous Systems of Invertebrates, vol I, W.H. Freeman, San Francisco, 1965, pp. 479–480.
4. Ocelli of hydromedusae;Singla;Cell. Tiss. Res.,1974
5. Fine structure of the ocellus of Sarsia tubulosa (Hydrozoa, Anthomedusae);Singla;Zoomorphology,1982