| original |
Silurian |
|
USSR(Estonian SSR) |
Eisenack,A. On Hystrichospheres and other microffossils of the Baltic Silurian and Cambrian |
1951 |
| details |
Early Ordovician |
|
USSR(Estonian SSR) |
Eisenack,A. Microfossils of the Ordovician from the Baltic area.1. |
1958 |
| details |
Silurian |
|
USSR(Estonian SSR) |
Eisenack,A. Microfossils of the Ordovician from the Baltic area.1. |
1958 |
| 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 |