Citation: S. Berger et al., Influence of ecological conditions on magnesium and strontium content and ultrastructure of the calcareous skeleton of Bornetella sphaerica (ZARNADINI), Dasycladales, Palaontologische Zeitschrift Palaontologische Zeitschrift (Print);Journal of Palaontologische Gesellschaft Scientific contributions to palaeontology, 71(3/4), 1997, pp. 189-195