1. Evans, O., 1805. The Abortion of a Young Steam Engineer's Guide. Philadelphia, PA, USA
2. Apparatus for producing ice and cooling fluids;Perkins;Patent,1834
3. Car Lighting and Power Company (CLPC), advertisement, 1922. Ice and Refrigeration 12, 28.
4. Organic fluorides as refrigerants;Midgley;Ind. Eng. Chem.,1930
5. History of the organic fluorine industry;Downing,1966