Boev, Z., Kovachev, D., 1998. Buteo spassovi sp. n. — a Late Miocene Buzzard (Accipitridae, Aves) from SW Bulgaria. — Geologica Balcanica, 29 (1—2): 125—129.
Spassov, N., 2000. The Turolian Hipparion-fauna and the character of the environment in the late Miocene of South-East Bulgaria. — Review of the Bulgarian Geological Society, Sofia, 61 (1—3): 47—59.
Kovachev, D., 2001. Description d’un squelette complet de Metailurus (Felidae, Carnivora, Mammalia) du Miocène supérieur de Bulgarie. — Geologica Balcanica, 31: 71—88.
Markov, G. N., Spassov, N., Simeonovski, V., 2002. Reconstruction of the facial morphology of Deinotherium gigantissimum Stefanescu, 1892 (based on the material from Ezerovo, South Bulgaria). — Historia naturalis bulgarica, 14: 141—144.
Spassov, N., 2002. The Turolian Megafauna of West Bulgaria and the character of the Late Miocene “Pikermian biome”. — Bollettino della Societa Paleontologica Italiana, 41 (1): 69—81.
Geraads, D., Spassov, N., Kovachev, D., 2001. New Chalicotheriidae (Perissodactyla, Mammalia) from Bulgaria. — J. of Vertebrate Paleontology, 21 (3): 596—606.
Kostopoulos, D., Spassov, N., Kovachev, D., 2001. Contribution to the study of Microstonyx: the Bulgarian case. — Geodiversitas, Paris, 23 (3): 41—437.
Христова, Л., Ковачев, Д., Спасов, Н., 2002. Хипарионите (Equidae, Mammalia) от късномиоценското находище Хаджидимово, Югозападна България. — Списание на Българското геологическо дружество, 63 (1—3): 89—98.
Geraads, D., Spassov, N., Kovachev, D., 2003. Palaeoreas lindermayeri (Wagner, 1848) from the upper Miocene of Bulgaria, and a revision of the species. — Geodiversitas, Paris, 25 (2): 405—415.
Koufos, G., Spassov, N., Kovachev, D., 2003. Study of Mesopithecus (Primates, Cercopithecoidea) from the Late Miocene of Bulgaria. — Palaeontographica, A, 269 (1—3): 39—91.
Hristova, L., Kovachev, D., Spassov, N., 2003. Hipparion brachypus Hensel, 1862 from the Late Miocene of Hadjidimovo, Southwestern Bulgaria. — Comptes rendus de l’Academie bulgare des Sciences, 56 (2): 77—84.
Христова, Л. 2003. Хипарионите (род Hipparion Christol 1832) от района на гр. Хаджидимово (късен миоцен, Югозападна България): таксономия и палеоекология. Дисертационен труд за присъждане на образователната и научна степен Доктор, Геологически институт-БАН, 131+24 стр.
Марков, Г. Н., 2004. Фосилните хоботни (Proboscidea, Mammalia) на България. Дисертационен труд за присъждане на образователната и научна степен Доктор, НПМ-БАН, София, 225+81 стр.
Spassov, N., Geraads, D., 2004. Tragoportax Pilgrim and Miotragocerus Stromer (Mammalia, Bovidae) from the Turolian of Hadjidimovo, Bulgaria, and a revision of the Late Miocene Mediterranean Boselaphini. — Geodiversitas, 26 (2): 339—370.
Spassov, N., Geraads, D., Kovachev, D., 2005. Tragoportax Pilgrim and Miotragocerus (Pikermicerus) Kretzoi (Mammalia, Bovidae) from the Turolian of Bulgaria. — Geologica Balcanica, 34 (3—4): 89—109.
Geraads, D., Spassov, N., Kovachev, D., 2005. Giraffidae (Artiodactyla, Mammalia) from the late Miocene of Kalimantsi and Hadjidimovo, South-Western Bulgaria. — Geologica Balcanica, 35 (1—2): 11—18.
Geraads, D., Spassov, N., Kovachev, D., 2006. The Bulgarian Chalicotheriidae (Mammalia): an update. — Revue de paléobiologie, Genève, 25 (2): 429—437.
Merceron, G., Zazzo, A., Spassov, N., Geraads, D., Kovachev, D., 2006. Bovid Paleoecology and paleoenvironments from the Late Miocene of Bulgaria: evidence from dental microwear and stable isotopes. — Palaeogeography, Palaeoclimatology, Palaeoecology, 241: 637—654.
Geraads, D., Spassov, N., Kovachev, D., 2006. A new Sporadotragus (Bovidae, Mammalia) from the late Miocene of Bulgaria. — Rivista Italiana di Paleontologia e Stratigrafia, 112 (3): 473—479.
Boev, Z., Kovachev, D., 2007. Euroceros bulgaricus gen. nov., sp. nov. from Hadzhidimovo (SW Bulgaria) (Late Miocene) — the first European record of Hornbills (Aves: Coraciiformes). — Geobios, 40: 39—49.
Markov, G. N., 2008. The Turolian proboscideans (Mammalia) of Europe: preliminary observations. — Historia naturalis bulgarica, 19: 153—178.
Kovachev, D., Atanasova, N., 2008. On the presence of genus Hystrix (Rodentia) in the Upper Maeotian from the region south of Hadzhidimovo town, Blagoevgrad district. — Review of the Bulgarian Geological Society, 69: 21—26.
Boev, Z., Spassov, N., Kovachev D., 2008. First Remains of Fossil Ostriches (Aves: Struthioniformes — Struthionidae) from Bulgaria. — Acta zoologica bulgarica, 60 (1): 89—98.
Geraads, D., Spassov, N., 2009. Rhinocerotidae (Mammalia) from the late Miocene of Bulgaria. — Palaeontographica, A, 287 (4—6): 99—122.
Boev, Z., Spassov, N., 2009. First Record of ostriches (Aves, Struthioniformes, Struthionidae) from the late Miocene of Bulgaria with taxonomic and zoogeographic discussion. — Geodiversitas, 31 (3): 493—507.
Hristova, L., 2009. Ontogeny and variability in the cheek region of hipparions from the Late Miocene locality Hadzhidimovo-1, Southwest Bulgaria. — Rivista Italiana di Paleontologia e Stratigraphia, 115 (1): 123—130.
Boev, Z., 2011. Falco bulgaricus sp. n. (Aves, Falconiformes) from the Middle Miocene of Hadzhidimovo (SW Bulgaria). — Acta zoologica bulgarica, 63 (1): 17—35.
Kovachev, D., 2012. A complete skeleton of Adcrocuta eximia (Roth and Wagner, 1854) from the Upper Maeotian (Turolian) of Hadzhidimovo, SW Bulgaria. — Geologica Balcanica 41 (1—3): 77—95.
Hristova, L. 2012. About the age of the Late Miocene localities of the Kalimantsi fossiliferous area on the basis of Cremohipparion (Perissodactyla, Equidae) skull morphology polymorphism. — Historia naturalis bulgarica, 20: 143—150.
Clavel, J., Merceron, G., Hristova, L., Spassov, N., Kovachev, D., Escarguel, G., 2012. On Mesopithecus habitat: Insights from late Miocene fossil vertebrate localities of Bulgaria. — Journal of Human Evolution, 63 (1): 162—179.
Boev, Z., 2012. Circaetus rhodopensis sp. n. (Aves, Accipitriformes) from the Late Miocene of Hadzhidimovo (SW Bulgaria). — Acta zoologica bulgarica, 64 (1): 5—12.
Markov, G. N., Kovachev, D., Tassy, P. 2014. A juvenile mandible of “Mastodon” grandincisivus Schlesinger, 1917 from Hadzhidimovo, SW Bulgaria. In: Kostopoulos, D. S., Vlachos, E., Tsoukala, E. (eds), Abstract Book of the VIth International Conference on Mammoths and Their Relatives. Scientific Annals of the School of Geology, Special Volume 102, 116.
Geraads, D., Spassov, N., 2016. Musteloid carnivores from the upper Miocene of South-Western Bulgaria, and the phylogeny of the Mephitidae. — Geodiversitas 38 (4): 543—558. https://doi.org/10.5252/g2016n4a5
Li, Y., Spassov, N., 2017. A new species of Paramachaerodus (Mammalia, Carnivora, Felidae) from the late Miocene of China and Bulgaria, and revision of Promegantereon Kretzoi, 1938 and Paramachaerodus Pilgrim, 1913. — Paläontologische Zeitschrift, 3 (91): 409—426; https://doi.org/10.1007/s12542-017-0371-7
Geraads, D., Spassov, N., 2020. A skull of Machairodus (Felidae, Mammalia) from the late Miocene of Hadjidimovo (Bulgaria), and its place in the evolution of the genus. — Geodiversitas 42 (9): 123—137.
Boev, Z., 2022. Additional material of Buteo spassovi Boev & Kovachev, 1998 from the Upper Miocene locality Hadzhidimovo (Blagoevgrad region, SW Bulgaria). — Geologica Balcanica, 51 (3): 17—19. [PDF]