Includes some Jurassic articles, such as:
Ivanov M., Stoykova K., Idakieva V. (2009) Revision of the ammonite criteria for the Jurassic—Cretaceous boundary in Bulgaria // National conference Geoscience 2009. Proceedings. Sofia: Bulgarian geological society. P.57-58.
pdf: http://www.bgd.bg/CONFERENCES/Geonauki_2009/Sbornik/PDF/22.pdf
In this study the ammonite zone Durangites spp. (Upper Tithonian) is recognized for the first time in Bulgaria. Authors propose a new position for the Jurassic—Cretaceous (J/K) boundary by ammonites in Bulgaria: between the zones Durangites spp. (Upper Tithonian) and Berriasella jacobi (Lower Berriasian). Thus, the lower boundary of the Cretaceous System in Bulgaria will be fixed on the first occurrence of Berriasella jacobi and shall be consistent to the widely accepted ammonite criteria for the J/K boundary in the Tethyan area.

Lakova I, Petrova S. (2009) Calpionellid zonation of the Tithonian, Berriassian and Valangian around the village of Gintsi, West Balkan Mountains // National conference Geoscience 2009. Proceedings. Sofia: Bulgarian geological society. P.51-52.
pdf: http://www.bgd.bg/CONFERENCES/Geonauki_2009/Sbornik/PDF/19.pdf