2 http://hdl.handle.net/10338.dmlcz/142158 2 A contribution to the conductivity of photographic emulsions http://hdl.handle.net/10338.dmlcz/142159 A contribution to the conductivity of photographic emulsions Some problems of cometary physics investigated on the basis of photometric data (Part two) http://hdl.handle.net/10338.dmlcz/142157 Some problems of cometary physics investigated on the basis of photometric data (Part two)