1. W. Biltz and E. Wilke-Dörfurt, “On Rb2S5 andCs2S5,≓Ber: Deut. Chem. Ges., 38, 123–130 (1905) in German. (Equi Diagram; Experimental)
2. W. Biltz andE. WilkeDörfim, “On the Sulfides of RbandCs,≓Z Anorg. Chem., 48(4), 297–318 (1906) in German. (Equi Diagram; Experimental; #)
3. W. Biltz and E. Wilke≈Dörfurt, “The Sulfides of Rb and Cs,≓Z.Anorg. Chem., 50(1), 67–81 (1906) in German. (Equi Diagram; Experimental)
4. E. Rengade and N. Costeanu, “On the Anhydrous Monosulfides of the Alkali Metals,≓Bull. Soc. Chim. Fr., 4th Ser., 15, 717–723 (1914) in French. (Equi Diagram, Thermo; Experimental)
5. J.W. Mellor.A Comprehensive Treatise on Inorganic and Theoretical Chemistry, Longmans, Green and Co., New York, NY (1922). (Equi Diagram; Compilation)