2009. ONTOGENY AND VARIABILITY IN THE CHEEK REGION OF HIPPARIONS FROM THE LATE MIOCENE LOCALITY HADZHIDIMOVO-1, SOUTHWEST BULGARIA. RIVISTA ITALIANA DI PALEONTOLOGIA E STRATIGRAFIA . 115, 1 (Mar. 2009). DOI:https://doi.org/10.13130/2039-4942/5924.