The Families Syracosphaeraceae, Rhabdosphaeraceae, and Calciosoleniaceae are tentatively retained in polymorphic Order Syracosphaerales Hay, 1977
Hay, W. W., (1977): Calcareous nannofossils. In, Ramsay, A. T. S. (ed.) - Oceanic Micropalaentology. Academic Press, London 1055-1200.