Heliolithus aktasii Varol, 1989c
Varol, O., 1989c. Palaeocene calcareous nannofossil biostratigraphy. In: Crux, J. A. & van Heck, S. E. (eds), Nannofossils and their applications. Proceedings of the 2nd INA Conference, London 1987. - British Micropalaeontological Society Publication Series 265-310.