Bison et al., 2004
From dinoflaj3
Bison, K-M., Wendler, J., Versteegh, G.J.M. and Willems, H., 2004: Tetratropis terrina sp. nov., a new calcareous dinoflagellate cyst from the Upper Campanian polyplocum zone of Lägerdorf (NW Germany). Journal of Micropalaeontology, v.23, p.127-132.