| original |
Givetian |
|
Ohio |
Wicander,R. et al. Systematics and biostratigraphy of the organic-walled microphytoplankton from the Middle Devonian, (Givetian), Silica Formation, Ohio, USA. |
1981 |
| details |
Givetian |
|
Ohio |
Wicander,R. A catalogue and biostratigraphic distribution of North American Devonian acritarchs. |
1983 |
| details |
Early Givetian |
Middle Givetian |
North America |
Wicander,R. Middle Devonian acritarch biostratigraphy of North America |
1984 |
| details |
Givetian |
|
Nd |
Fensome,R.A. et al. Acritarchs and Fossil Prasinophytes: An index to genera, species and infraspecific taxa. |
1990 |
| details |
Strunian |
Early Tournaisian |
Canada(Saskatchewan) |
Playford,G. et al. Miospores and organic-walled microphytoplankton of Devonian-Carboniferous boundary beds, (Bakken Formation), southern Saskatchewan: A systematic and stratigraphic appraisal. |
1993 |