Petŭr Beron

Peshteri i khora

Peshteri i khora

2012

Caves and speleology in Bulgaria

2006

Biodiversity of eastern Rhodopes (Bulgaria and Greece)

2004

Zhivot li be da go opishesh

Zhivot li be da go opishesh

2003

Bŭlgarski peshteri

Bŭlgarski peshteri

1900