1996   Michel Pourchet, Marie Antoinette Melieres, Emil Silvestru, Géza Rajka, F.Candaudap, Jean-Perre Carbonnel -  Radionuclides in a
            caves lake sediment core from Ghetarul de sub Zgurasti (jud. Alba,
           România). Theoretical and Applied Karstology, 9: 23-28.

1998 - 1999  Gh. Racovita, O. Moldovan, G. Rajka -  Donnees preliminaires sur l’environnement de la Grotte des Ours en regime
            d’exploitation touristique. Theoretical and Applied Karstology, 11/12: 61-74

1998-1999  Plesa, O. Moldovan, Gh. Racovita, A. Fekete, S. Iepure, G. Rajka - Ecological researches concerning groundwater fauna from
            Somesul Cald valley (Apuseni Mountains). Report for the National Agency of Science, Technology and Innovation, 100 pp.

1999  Plesa, A. Fekete, G. Rajka, R. Buzila -  Some data concerning the biodiversity of stygofauna in the River Somesul Cald / Meleg
            Szamos basin.  TISCIA monograph series - The Somes / Szamos River Valley, A study of the geography, hydrobiology and ecology of
            the river system and its environment. 1999.