Kojumdgieva, E. (1968). Predstavitelite na rod Congeria v neogena na Severozapadna Bulgariya i tyakhnata filogeniya i paleoekologiya [The representatives of the genus Congeria in the Neogene of northwest Bulgaria and their phylogeny and paleoecology]. Izvestiya na Geologicheskiya Institut, Seriya Paleontologiya. 17: 173-227.
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Kojumdgieva, E.
1968
Predstavitelite na rod <i>Congeria</i> v neogena na Severozapadna Bulgariya i tyakhnata filogeniya i paleoekologiya [The representatives of the genus <i>Congeria</i> in the Neogene of northwest Bulgaria and their phylogeny and paleoecology]
Izvestiya na Geologicheskiya Institut, Seriya Paleontologiya
17: 173-227
Publication
in Bulgarian with extended Russian and French summaries