In addition, Jaroslav and Petr Kraft, with colleagues from Prague, organised in 1999 a highly successful 9th ISOS conference (International Symposium on Ordovician System) in Prague.
Jaroslav a Petr Kraftovi také s kolegy v Praze spoluorganizovali v roce 1999 devátou konferenci ISOS (International Symposium on Ordovician System) v Praze.