Kostov, R. I.

• Τόμ. 100 (2010) - Άρθρα
  Gem minerals and materials from the neolithic and chalcolithic periods in Bulgaria and their impact on the history of gemmology
  Λεπτομέρειες  PDF
• Τόμ. 39, Αρ. 1/2 (2010) - Επιτομές
  Gem minerals and materials from the Neolithic ans Chalcolithic periods in Bulgaria and their impact on the history of gemmology
  Λεπτομέρειες  PDF