Waizumi K , Masuda H , Ohtaki H , Scripkin M Y , Burkov K A , American Mineralogist , 76 (1991) p.1884-1888, Crystallographic investigations of [Mg(H2O)6]XCl3 double salts, (X = K, Rb, Cs, NH4): Crystal structure of [Mg(H2O)6]CsCl3, Note: modified perovskite structure