Cavis Negra – performances in the caves and subterranes of Slovenian Karst region
1991, U-matic, Egon March Institute & Andrej Kregar, VPK, Ljubljana 1991, duration 10', Camera: Leon Oblak, Photo / Slides: Smiljan Šiska, Dir., Script: Marko Košnik, Edit: Andrej Kregar

As a conclusion of their three-year acoustic investigations in subterranes of the Slovene Karst region, Etbin Stefancic, Andrej Trobentar and Marko Kosnik performed a concert for video camera in the Rančečka water reservoir and the Vilenica Cave.

Cavis Negra (group for audiovisual performances) works:
- Rancecka water reservoir, Vilenica Cave, 1985–1987
Marko Košnik, Etbin Stefančič, Bojan Štokelj, Andrej Žibert, Marko Modic, Božo Ogorevc, Dino Goyo, Simon Horvat, Pavel Okorn
- Radio theatre program in Cankarjev dom, 1985 
Marko Košnik, Etbin Stefančič, Bojan Štokelj, Andrej Žibert, Pavel Okorn
- Multimedia performance, Cankarjev dom, Ljubljana, 1985
Bojan Štokelj, Edbin Stefančič, Marko Modic, Marko Košnik, Marjian Rudel, Milan Hodošček, Božo Ogorevc, Lado Jakša, NIno De Gleria, Andrej Žibert, Uroš Lovšin, Pavel Okorn, Bojan Brecelj, Smiljan Šiška, Susana Diez Rupnik

(Source: Egon March Institute at YouTube)