Kovatcheva, T. (1969). On the age of the Urgonian sediments in the Lovech area, based on their foraminiferal content. Bulletin of the Geological Institute, series Paleontology, Publishing House of the Bulgarian Academy of Sciences. 18: 25-46 (Bulgarian with Summary in Russian and English).
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Kovatcheva, T.
1969
On the age of the Urgonian sediments in the Lovech area, based on their foraminiferal content
Bulletin of the Geological Institute, series Paleontology, Publishing House of the Bulgarian Academy of Sciences
18: 25-46 (Bulgarian with Summary in Russian and English)