3Kost L A,Novikova H N,Sin'kova L A.Production of Alumina Concentrates from Kaolinite-containing Cole Wastes[J].Solid Fuel Chemistry,1979 (3).
4Burger Kurt.Kaolin-Kohlentonseine im floezfuehrenden Oberkarbon des Niedereheinisch-Westfaelischen Steinkohlenreviers (Kaolin coal ton-steins from the Upper Carboniferous of the Lower Rhine-Westphalian coal district)[J].Geologische Rundschau,1980 (2).
5Burger Kurt,Bandelow Friedrich K,Bieg Gerd.Pyroclastic Kaolin cola ton-steins of the Upper Carboniferous of Zonguldak and Amasra Turkey[J].International journal of coal geology,2000(1).