| original |
Early Oligocene |
|
USSR(WSL) |
Ushakova,M.V. et al. Lower Oligocene. (In: Stratigraphy of the Mesozoic and Cenozoic of the Western Siberian Lowlands. V.F.Kozyreva, editor) |
1957 |
| original |
Eocene |
|
Japan(Hokkaido I.) |
Tokunaga,S. Fossil pollen and spore from the known coal seams in the Bibai area, Ishikari Coal Field, Hokkaido. |
1955 |
| original |
Early Tertiary |
|
Japan(Hokkaido I.) |
Tokunaga,S. Pollen analysis of the known coal seams in the Biba Bibai area, Sorachi District, Ishikari Coal Fields, Hokkaido. |
1955 |