| original |
Ordovician |
|
E.Germany |
Eisenack,A. Axisphaeridium, n.gen, an axialsymmetrical Hystrichosphere of the Baltic Ordovician |
1967 |
| details |
Early Ordovician |
|
Sweden |
Eisenack,A. On the reproduction of Palaeozoic hystrichospheres. |
1968 |
| details |
Ordovician |
|
Germany |
Eisenack,A. et al. Catalog of fossil dinoflagellates, hystrichospheres and related microfossils. Acritarchs. |
1973 |
| details |
Early Paleozoic |
|
Nd |
Cramer,F.H. et al. Lower Paleozoic acritarchs. |
1979 |
| details |
Ordovician |
|
Nd |
Fensome,R.A. et al. Acritarchs and Fossil Prasinophytes: An index to genera, species and infraspecific taxa. |
1990 |
| details |
Llandeilian |
Early Caradocian |
USSR(Estonian SSR) |
Uutela,A. et al. Ordovician acritarchs from the Rapla borehole, Estonia |
1991 |